System and method for operating industrial gas turbine apparatus and gas turbine electric power plants preferably with a digital computer control system

ABSTRACT

A gas turbine power plant is provided with an industrial gas turbine which drives a rotating brushless exciter generator coupled to a power system through a breaker. One or more of the turbine-generator plants are operated by a hybrid digital computer control system during sequenced startup, synchronizing, load, and shutdown operations. The program system for the computer and external analog circuitry operate in a multiple gas turbine control loop arrangement. Logic macro instructions are employed in programming the computer for logic operations of the control system.

This is a continuation, of application Ser. No. 82,470 filed Oct. 20,1970.

CROSS-REFERENCE TO RELATED APPLICATIONS

Reference is made to a deposited microfiche appendix forming a parthereof and having therein 17 microfiche with 1070 frames including titleframes.

Ser. No. 82,469 filed on Oct. 20, 1970 by R. Kiscaden and R. Yannone,entitled improved system and method for accelerating and sequencingindustrial gas turbine apparatus and gas turbine electric power plantspreferably with a digital computer control system, and assigned to thepresent assignee.

Ser. No. 82,467 filed on Oct. 20, 1970 by J. Rankin and T. Reed,entitled improved control computer programming method and improvedsystem and method for operating industrial gas turbine apparatus, andetc., and assigned to the present assignee.

U.S. Pat. No. 3,919,623 filed by J. Reuther on Dec. 6, 1971, entitledFuel Transfer Control, and assigned to the present assignee.

Ser. No. 99,491 filed on Dec. 18, 1970 by J. Ruether, entitled AutomaticSynchronizing, and assigned to the present assignee.

U.S. Pat. No. 4,031,407 filed on Dec. 18, 1970 by T. Reed, entitledAutomatic Synchronizing, and assigned to the present assignee.

BACKGROUND OF THE INVENTION

The present invention relates to gas or combustion turbine apparatus,gas turbine electric power plants and control systems and operatingmethods therefor.

Industrial gas turbines may have varied cycle, structural andaerodynamic designs for a wide variety of uses. For example, gasturbines may employ the simple, regenerative, steam injection orcombined cycle in driving an electric generator to produce electricpower. Further, in these varied uses the gas turbine may have one ormore shafts and many other rotor, casing, support, and combustion systemstructural features which can vary relatively widely among differentlydesigned units. They may be aviation jet engines adapted for industrialservice as described for example in an ASME paper entitled "The Prattand Whitney Aircraft Jet Powered 121MW Electrical Peaking Unit"presented at the New York Meeting in November-December 1964.

Other gas turbine uses include drive applications for pipeline orprocess industry compressors and surface transportation units. Anadditional application of gas turbines is that which involves recoveryof turbine exhaust heat energy in other apparatus such as electric poweror industrial boilers or other heat transfer apparatus. More generally,the gas turbine air flow path may form a part of an overall processsystem in which the gas turbine is used as an energy source in the flowpath.

Gas turbine electric power plants are usable in base load, mid-rangeload and peak load power system applications. Combined cycle plants arenormally usable for the base or mid-range applications while the powerplant which employs a gas turbine only as a generator drive typically ishighly useful for peak load generation because of its relatively lowinvestment cost. Although the heat rate for gas turbines is relativelyhigh in relation to steam turbines, the investment savings for peak loadapplication typically offsets the higher fuel cost factor. Anothereconomic advantage for gas turbines is that power generation capacitycan be added in relatively small blocks such as 25MW or 50MW as neededfor expected system growth thereby avoiding excessive capitalexpenditure and excessive system reserve requirements. Furtherbackground on peaking generation can be obtained in articles such as"Peaking Generation" a Special Report of Electric Light and Power datedNovember 1966.

Startup availability and low forced outage rates are particularlyimportant for peak load power plant applications of gas turbines. Thus,reliable gas turbine startup and standby operations are particularlyimportant for power system security and reliability.

In the operation of gas turbine apparatus and electric power plants,various kinds of controls have been employed. Relay-pneumatic typesystems form a large part of the prior art. More recently, electroniccontrols of the analog type have been employed as perhaps represented byU.S. Pat. No. 3,520,133 entitled Gas Turbine Control System and issuedon July 14, 1970 to A. Loft or by the control referred to in an articleentitled Speedtronic Control, Protection and Sequential System anddesignated as GER-2461 in the General Electric Gas Turbine ReferenceLibrary. A wide variety of controls have been employed for aviation jetengines including electronic and computer controls as described forexample in a March 1968 ASME Paper presented by J. E. Bayati and R. M.Frazzini and entitled "Digatec (Digital Gas Turbine Engine Control)", anApril 1967 paper in the Journal of the Royal Aeronautical Societyauthored by E. S. Eccles and entitled "The Use of a Digital Computer forOn-Line Control of a Jet Engine", or a July 1965 paper entitled "TheElectronic Control of Gas Turbine Engines" by A. Sadler, S. Tweedy andP. J. Colburn in the July 1965 Journal of the Royal AeronauticalSociety. However, the operational and control environment for jet engineoperation differs considerably from that for industrial gas turbines. Inreferencing prior art publications or patents as background herein, norepresentation is made that the cited subject matter is the best priorart.

Generally, the operation of industrial gas turbine apparatus and gasturbine power plants have been limited in flexibility, response speed,accuracy and reliability. Further limits have been in the depth ofoperational control and in the efficiency or economy with which singleor multiple units are placed under operational control and management.Limits have existed on the economics of industrial gas turbineapplication and in particular on how close industrial gas turbines canoperate to the turbine design units over various speed and/or loadranges.

In gas turbine power plants, operational shortcomings have existed withrespect to plant availability and load control operations. Turbine surgelimit control operations have been limited particularly during startup.Temperature limit control has been less protective and less responsivethan otherwise desirable.

Generally, overall control loop arrangements and control systemembodiments of such arrangements for industrial gas turbines have beenless effective in operations control and systems protection than isdesirable. Performance shortcomings have also persisted in theinterfacing of control loop arrangements with sequencing controls.

With respect to industrial gas turbine startup, turbine operating lifehas been unnecessarily limited by conventional startup schemes.Sequencing systems have typically interacted with startup controls lesseffectively than desirable from the standpoint of turbine and powerplant availability. More generally, sequencing systems have provided forsystematic and protective advance of the industrial gas turbineoperations through startup, run and shutdown but in doing so have beenless efficient and effective from a protection and performancestandpoint than is desirable.

Restrictions have been placed on operations and apparatus managementparticularly in gas turbine power plants in the areas of maintenance andplant information acquisition. Further management limits have existedwith respect to plant interfacing with other power system points,operator panel functionality, and the ability to determine plantoperations through control system calibration and parameter changes.

SUMMARY OF THE INVENTION

One or more industrial gas turbines or gas turbine-generator powerplants are operated by a control system which preferably employs aprogrammed digitral computer in a hybrid control system arrangement. Thecontrol system operates in a gas turbine control loop arrangementpreferably to control fuel flow and thereby provide load and loadingrate control over the turbine and generator or other unit and furtherprovide speed, surge and temperature limit control with nonlinearcontrol loop characterization. In power plant applications, thepreferred computer provides generator control actions and it interfaceswith the operator preferably through a central operator's panel toprovide extended power plant management and operational benefits.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a top plan view of a gas turbine power plant arranged tooperate in accordance with the principles of the invention;

FIGS. 2 and 3 show respective electrical systems usable in the operationof the gas turbine power plant of FIG. 1;

FIG. 4 shows a schematic view of a rotating rectifier exciter and agenerator employed in the gas turbine power plant of FIG. 1;

FIG. 5 shows a front elevational view of an industrial gas turbineemployed in the power plant to drive the generator and it is shown withsome portions thereof broken away;

FIGS. 6-8 show a fuel nozzle and parts thereof employed in the gasturbine of FIG. 5;

FIGS. 9 and 10 respectively show schematic diagrams of gas and liquidfuel supply systems employed with the gas turbine of FIG. 5;

FIGS. 11A-G show various performance curves associated with theturbine-generator unit of FIG. 4;

FIG. 12 shows a block diagram of a digital computer control systememployed to operate the gas turbine power plant of FIG. 1;

FIGS. 13A-D show various schematic diagrams of control loops which maybe employed in operating the computer control system of FIG. 12 and thepower plant of FIG. 1;

FIGS. 14-17 illustrate various curve data employed in the control systemcomputer in the operation of the gas turbine power plant;

FIG. 18 shows a sequence chart for startup and shutdown operations ofthe gas turbine power plant;

FIGS. 19A-B show a cable and wiring diagram employed for a computercontrol system and various power plant apparatus elements in a preferredembodiment of the invention;

FIG. 20A-B shows a schematic diagram of analog circuitry associated withthe computer in the control system to provide control over gas turbinefuel supply sysem operations and certain other plant functions;

FIGS. 21-23 show certain control signal characteristics associated withthe analog circuitry of FIG. 20;

FIGS. 24A, 24B, 24C and 25 respectfully respectively show front planviews of a local operator's panel and a remote operator's panel employedin the control system;

FIG. 26 shows a general block diagram of the organization of a programsystem employed in the control system computer;

FIGS. 27 and 28 show respective flowcharts representative of operationsassociated with the operator's panel;

FIG. 29 shows a flowchart representative of an analog scan programassociated with the computer for the acquisition of analog data from thegas power plant;

FIGS. 30A-C show flowcharts associated with an analog output programwhich is employed in the computer to cause the generation of outputanalog signals;

FIG. 31 illustrates a flowchart for a sequencing program associatedprincipally with startup operations for the gas turbine;

FIG. 32 shows a data flow diagram which illustrates the manner in whichthe sequencing program is executed to provide multiple power plantoperations with a single control computer;

FIGS. 33Aa 33Ab, 33B1a 33B1b 33B2 33C1 33C2 33D2 33D1a 33D1b 33Ea 33Eb33Fa and 33Fb show a plurality of logic diagrams representative of tehsequencing logic performed by the sequencing program;

FIG. 34 shows a block diagram of a control loop arrangement implementedin the preferred embodiment;

FIG. 35 shows a data flow diagram associated with control programoperations during controlled operation of multiple gas turbine powerplants with a single control computer;

FIG. 36 illustrates a flowchart representative of preprocessoroperations in the flow diagram of FIG. 35;

FIG. 37 illustrates a flowchart which represents control programoperations in the preferred embodiment;

FIG. 38 shows a more detailed flowchart for a speed reference generationfunction included in the program of FIG. 37;

FIG. 39 shows a more detailed flowchart for a gas turbine blade path andexhaust temperature limit function employed in the program of FIG. 37;

FIGS. 40A-E show respective control configurations of software elementsassociated respectively with Mode 0 through Mode 4 operations;

FIGS. 41A-B respectively show software control configurations for theblade path temperature and exhaust temperature limit functions;

FIG. 42 illustrates a flowchart which represents the operations of ananalog input routine employed in the control program;

FIG. 43 shows a flowchart for a high temperature finding routineassociated with the blade path and exhaust temperature processing in theanalog input routine;

FIGS. 44 and 45 respectively illustrate flowcharts representative ofdigital integration and differentiation functions employed in thecontrol program operations;

FIG. 46 shows a flow diagram for control program operations whichprovide load control and load limit functions for the gas turbine powerplant;

FIG. 47 illustrates a flowchart for an alarm program included in theprogram system;

FIGS. 48 and 49 respectively show flowcharts for a thermocouple checkprogram and a log program employed in programmed computer operations;

FIGS. 50A-D show the flowcharting which represents a program used toconvert analog input system units to engineering units for log programoperations;

FIG. 51 shows a flowchart for a program which converts engineering unitsto analog input system limits;

FIG. 52 illustrates a flowchart for a load rate limit function employedin the load control and limit operations illustrated in FIG. 46;

FIG. 53 shows a flowchart for a rate function employed in temperaturelimit operations.

FIG. 54 shows a speed curve for calculation of speed reference changes.

DESCRIPTION OF THE PREFERRED EMBODIMENT A. POWER PLANT 1. GeneralStructure

More particularly, there is shown in FIG. 1 a gas turbine electric powerplant 100 which includes an AC generator 102 driven by a combustion orgas turbine 104 through a reduction gear unit 106. In this applicationof the invention, the gas turbine 104 is the W-251G simple cycle typemanufactured by Westinghouse Electric Corporation. In other power plantgenerator applications, other industrial drive applications, andcombined steam and gas cycle applications of various aspects of theinvention, industrial gas turbines having larger or smaller powerratings, different cycle designs, different number of shafts orotherwise different from the W-251G can be employed.

Generally, the electric power plant 100 is designed to provide aneconomical solution to many types of power generation problems such asbase or intermediate system low use factor. Thus, to meet powergenerator peaking requirements a single plant 100 or multiple plantunits 100 can be purchased simultaneously or over a period of time tomeet system power generation needs at relatively reduced investmentcost. Another typical use of the plant 100 is where continuous powergeneration is desired and the exhaust heat from the gas turbine 104 isused for a particular purpose such as for feedwater heating, boilers, oreconomizers.

In addition to the advantage of relatively low investment cost, theplant 100 can be located relatively close to load centers as indicatedby system requirements without need for a cooling water supply therebyadvantageously producing a savings in transmission facilities. Further,the plant 100 can be unattended and automatically operated from a remotelocation.

Community acceptance of the plant 100 is enhanced by the use of inletand exhaust silencers 108 and 110 which are coupled respectively to theinlet and exhaust ductworks 112 and 114. Fast startup and low standbycosts are additional operating advantages characteristic to the plant100. Among additional advantages, the major components of the plant 100can be separately shipped to the plant site and site assembly can becompleted with relatively simple connections since most plant piping,wiring and testing can be done at the factory.

The plant 100 is provided with an enclosure (not shown) in the form of arigid frame-type sectional steel building. It comprises rigid structuralsteel frames covered by sectional type panels on the roof and the walls.The roof and wall construction is designed for minimum heat loss andminimum noise penetration while enabling complete disassembly whenrequired.

The foundation for the plant 100 is approximately 106 feet long if acontrol station is provided for a single plant unit. The foundationlength is increased to approximately 115 feet as indicated by thereference character 116 if space is provided for a master controlstation when up to three optional additional plant units are selected.

Digital computer and other control system circuitry in a cabinet 118provides for operation of the power plant 100 when a single plant unitis selected by the user. An operator's panel 120 is associated with thecontrol cabinet 118. In addition, an automatic send/receive printer 122and a protective relay panel 124 for sensing abnormal electric powersystem conditions are associated with the control cabinet 118. Thenumbers of basic, master and slave units 118 through 124 required in thepresent application of the invention for up to four plants like theplant 100 are indicated by the following table:

    ______________________________________                                        CONTROL ROOM OPTIONS                                                          Control Room                                                                            Slave Units                                                                              Quantities Per Unit                                      For       Served     124     118   122   120                                  ______________________________________                                        Basic Station                                                                           0          1       1     1     1                                    One Unit                                                                      Master For                                                                    Two Unit  1          1       2     1     2                                    Station                                                                       Master For                                                                    Three Unit                                                                              2          1       2     1     3                                    Station                                                                       Master For                                                                    Four Unit 3          1       3     1     4                                    Station                                                                       Slave Unit                                                                              0          1       0     0     0                                    ______________________________________                                    

Startup or cranking power for the plant 100 is provided by a startingengine 126 such as a diesel engine, a 600 HP diesel in the present case,or an electric induction motor unit. The starting engine 126 is mountedon an auxiliary bedplate and coupled to the drive shaft of the gasturbine 104 through a starting gear unit 128. A DC motor 154 operatesthrough a turning gear 156 which is also coupled to the gas turbineshaft through the starting gear 128 to drive the gas turbine at turninggear speed for at least the first sixty hours of nonoperating periods,or longer if turbine disc cavity temperature is excessive, in order toavoid thermally induced shaft bowing.

A motor control center 130 is also mounted on the auxiliary bedplate andit includes motor starters and other devices to provide for operatingthe various auxiliary equipment items associated with the plant 100.Motor control center 130 breakers are front mounted and the breakers andmotor starters are cable connected to a 480 volt power supply. Varioussignals from sensor or contact elements associated with the motorcontrol center 130 and with other devices mounted on the auxiliarybedplate are transmitted for use in the control system as consideredmore fully in connection with FIG. 12.

A plant battery 132 is disposed adjacent to one end of the auxiliarybedplate or skid. A battery charger (FIG. 12) is also included and it ispreconnected to the motor control center 130 through a breaker. Thebattery for example can be a heavy duty control battery of the typeEHGS-17 EXIDE rated at 125 volts, 60 cells. In this case, the battery iscapable of supplying adequate power for emergency lighting, auxiliarymotor loads, and DC computer and other control power for one hourfollowing shutdown of the plant 100 due to a loss of AC power.

More generally, the electrical power system for the plant 100 isdesigned to enable the plant 100 to operate without connection to thepower system, or to operate by accepting auxiliary power and otherconnections from the power system. However, one boundary condition isthat the plant 100 must have auxiliary power once it reaches synchronousspeed for power generation. Thus, although the plant 100 can be startedby use of the battery 132 and without auxiliary power, the requirementfor auxiliary power at synchronous speed must be met. If desired,electrical systems of basic design different from that of the describedsystem can be employed to provide auxiliary power for the plant 100.

One electrical system for the plant 100 is shown generally in FIG. 2.Once the plant 100 is in operation, the generator 102 transmits power tothe power system through a generator breaker 132 and a 13.8 KV bus 134to a main transformer 135 and a line breaker 137 to the power system.Auxiliary power for the plant 100 is obtained from the system through anauxiliary breaker 136 and an auxiliary power 480 volt bus 137. Thegenerator breaker 132 serves as a synchronizing and protectivedisconnect device for the plant 100.

If a suitable 480 volt source is not available in the power system, anauxiliary power transformer 138 can be provided in another generalsystem as shown in FIG. 3. A disconnect switch 140 is connected betweenthe transformer 138 and the station 13.8 KV bus 134.

If a firm reliable source of auxiliary power cannot be provided from thesystem, the arrangement as shown in FIG. 3 can provide for black plantstartup operation. With this arrangement, the gas turbine 104 may bestarted at any time, since the auxiliaries may be supplied from thegenerator 102 or from the system, whichever is energized. For a blackstart (with a dead system), the gas turbine 104 may be started at anytime for availability as a spinning standby source even though theexternal system is not ready to accept power from the generator 102.Further, the plant 100 can be separated from a system that is in troublewithout shutting the gas turbine 104 down. The breaker nearest the loadwould be tripped to drop the load and let the generator 102 continue torun and supply its own auxiliaries.

An additional advantage of the scheme shown in FIG. 3 is the protectionprovided if the connection to the system is vulnerable to a permanentfault between the gas turbine power plant 100 and the next breaker inthe system. The line breaker 137 would be the clearing breaker in caseof such a fault and the auxiliary system would remain energized from thegenerator 102 which would allow an orderly shutdown of the gas turbine104 or continued operation as standby.

The arrangement of FIG. 3 is used if the gas turbine 104 is programmedto start in the event of system low voltage or decaying frequency.Automatic startup brings the turbine 104 up to speed, closes thegenerator breaker 132 and supplies power to the auxiliary load. Theturbine-generator unit would then be running and would be immediatelyavailable when desired. The arrangement of FIG. 3 is also used if theturbine 104 is running and the system under-frequency or under-voltagesignal is used to separate the gas turbine 104 from the system.

A switchgear pad 142 is included in the plant 100 for 15 KV switchgearincluding the generator breaker as indicated by the reference characters144, 146 and 148. The auxiliary power transformer 138 and the disconnectswitch 140 are also disposed on the switchgear pad 142 if they areselected for use by the user. Excitation switchgear 150 associated withthe generator excitation system is also included on the switchgear pad142. The control system also accepts signals from certain sensor orcontact elements associated with various switchgear pad devices.

A pressure switch and gauge cabinet 152 is also included on theauxiliary skid. The cabinet 152 contains the pressure switches, gauges,regulators and other miscellaneous elements needed for gas turbineoperation.

A turbine high pressure cooling system includes a radiator air-to-aircooler designed for ambients up to 100° F. with the use of a pair ofdual speed fans. The radiator is associated with the necessaryinterconnecting piping to obtain high pressure compressor outlet air andto transmit the cooled pressurized air the the turbine parts.

A radiation-type air-to-oil cooler is employed for lubrication oilcooling. It is designed for ambients from 0° to 105° F. and it alsoemploys a dual speed fan. Generally, a shaft driven main lubricating oilpump supplies lubricating oil when the plant 100 is running. A DC motordriven auxiliary lubricating oil pump supplies sufficient oil forstarting and stopping. To safeguard against loss of lubricating oil, thestarting equipment is interlocked so that the plant 100 cannot bestarted under power without lubricating oil pressure. Further, duringrun operations the auxiliary lubricating oil pump starts automaticallyif the lubricating oil pressure becomes dangerously low. The auxiliarypump then serves to bring the gas turbine-generator unit to a standstillin the event the main lubricating oil pump has had a failure. Thefollowing list includes the main auxiliaries employed or optionallyemployed in the plant 100:

    ______________________________________                                                          Rating, HP                                                  A-C Drives                                                                    440 Volt, 3 Phase, 60 Cycle                                                                       Fuel Oil   Gas                                            ______________________________________                                        (1) Lube oil cooler fan                                                       (2 speed)           25         25                                             (2) Instrument air compressor                                                                     1.5        1.5                                            (3) Turbine enclosure exhaust                                                 fan                 2-2        2-2                                            (4) Turbine cooling air heat                                                  exchanger fan (2 speed)                                                                           2-5        2-5                                            (5) Lube oil circulating pump                                                                     20         20                                             (6) Evaporative cooler (optional)                                                                 10         10                                             (7) Vapor extractor for lube                                                                      1/2        1/2                                            Oil Fuel System, A-C Motors                                                   (1) Fuel oil (storage tank to unit)                                           transfer pump (optional)                                                                          5          --                                             (2) Atomizing air compressor                                                                      5                                                         (3)                                                                           D-C Drives - 125 Volts                                                        (1) Auxiliary lube oil pump                                                                       10         10                                             (2) Turning gear    5          5                                              (3) Fuel oil (storage tank to unit)                                           transfer pump (optional)                                                                          5          --                                             (4) Static inverter 3 KVA                                                     Heaters -                                                                     440 Volt, 3 Phase, 60 Cycle                                                   (1) Generator and Exciter space                                               heaters             9 KW                                                      (2) Building unit heaters                                                     (normal minimum ambient)                                                                          10 KW                                                     (3) Lube oil heater 18 KW                                                     (4) Diesel starter jacket water                                               heater              21/2KW                                                    Controls - 125 Volt D-C                                                                           1 KW                                                      ______________________________________                                    

The switchgear 144, 146 and 148 and the auxiliary protection and controlelements include, or optionally include, the following:

(1) 15 KV HVMC Switchgear

(a) 15 KV Switchgear with the following equipment:

Generator breaker type 150DHP500, 2000A. Non-segregated phase bus,generator to switchgear.

Auxiliary unit for PRX regulator.

3--2000/5 CT's for generator differential protection.

3--2000/5 CT's for relaying or metering.

3--Type SV lightning arresters.

3--Type FP capacitors.

2--14400/120 V PT's for metering, relaying and synchronizing(generator).

2--14400/120 V PT's for synchronizing (line side).

2--14400/120 V PT's for voltage regulator.

Provisions for outgoing conduit for cable to system.

2--1500 MCM per phase (out top or bottom).

(b) Optional 15 KV switchgear items.

750 2000A type DHP ACB for generator breaker (in place of 150DHP500).

1--2000/5 CT for regulator compensation.

Type DFS fused switch for auxiliary power transformer supply.

Provisions for connecting to system (in place of 1-a, Item 12).

Bus duct out top.

Roof bushings out top.

Type 150 DHP 500 line side breaker.

Type 150 DHP 750 line side breaker.

Bus ground fault relay system.

Tropicalization treatment.

(2) Generator Protection

(a) The basic generator protection equipment includes the followingitems:

SA-1 generator differential.

COQ negative sequence.

CW reverse power.

2-WL lockout relay.

COV voltage controlled overcurrent.

CV-8 generator ground relay.

(b) Optional Protection Items

CFVB voltage balance relay.

Unit differential relay.

HU

HU-1

WL lockout for use with 3-b, Item 2.

Neutral grounding reactor.

10 second rating

1 minute rating

CO-8 neutral ground (for use with grounding reactor)

2 Additional COV voltage controlled relays.

CV-7 over-under voltage relay (generator).

CV-7 over-under voltage relay (system).

KF underfrequency relay (generator).

KF underfrequency relay (system).

(3) Auxiliary System

(a) Motor control center with provisions for accepting auxiliary powerat 480 V-60 Hertz from plant source or customer source. The 125 V D-C issupplied from the plant battery. The motor control center is completewith the following:

Incoming main breaker A-C.

Individual fused control circuits.

Common control power transformer.

Type II-C wiring.

A-C starters for the following functions:

Air cooler fan high.

Air cooler fan low.

Lube oil cooler fan two speed.

Lube oil heater.

Diesel jacket heater.

Generator space heater.

Lube oil circulating pump.

Control air compressor.

Building heaters (2).

Vent fans (2).

Inlet heater.

Vapor extractor.

Battery charger breaker.

Distribution panelboard A-C 120/240 V.

Incoming breaker D-C.

D-C starters for the following functions:

Lube oil pump.

Turning gear.

Fuel transfer pump.

Distribution panelboard D-C 125 V.

(b) Motor control center options Starters for the following:

Evaporative cooler pump.

Fuel oil transfer pump.

Atomizing air compressor.

Spare

Main transformer auxiliary feeder breaker. Yard lighting feeder breaker.

(c) Miscellaneous auxiliary options Auxiliary transformer 13.8KV/480-2777 V, to be supplied from HVMC fused switch option, with thefollowing ratings:

150 KVA

225 KVA

500 KVA

750 KVA

PT's for 480 volt bus metering (WHM and volts).

CT's for 480 volt bus metering (WHM and amps).

LVME switchgear for auto-transfer from system to station 480 volt power.

2. Generator and Exciter

The generator 102 and its brushless exciter 103 are schematicallyillustrated in greater detail in FIG. 4. The rotating elements of thegenerator 102 and the exciter 103 are supported by a pair of bearings158 and 160. Conventional generator vibration transducers 162 and 164are coupled to the bearings 158 and 160 for the purpose of generatinginput data for the plant control system. Structurally, the generator 102and the exciter 103 are air cooled and located within an enclosure withsuitable ventilation and heating to provide for proper equipmentprotection. Filtered outside air is drawn through the enclosure by shaftmounted axial flow blowers to cool the equipment. Generator spaceheaters are sized correctly for the installation environment to preventcondensation during shutdown. A grounding distribution transformer withsecondary resistors (not indicated) is provided to ground the generatorneutral.

Resistance temperature detectors (six in this case) are embedded in thestator winding and thermocouples are installed to measure the air inletand discharge temperatures and the bearing oil drain temperatures asindicated in FIG. 4. Signals from all of the temperature sensors and thevibration transducers 162 and 164 are transmitted to the control system.Thermocouples (not indicated in FIGS. 1 or 4) associated with thereduction gear 106 similarly generate bearing temperature signals whichare transmitted to the control system.

In operation of the exciter 103, a permanent magnet field member 164 isrotated to induce voltage in a pilot exciter armature 166 which iscoupled to a stationary AC exciter field 168 through a voltage regulator170. Voltage is thereby induced in an AC exciter armature 172 formed onthe exciter rotating element and it is applied across diodes mountedwith fuses on a diode wheel 174 to energize a rotating field element 176of the generator 102. Generator voltage is induced in a stationaryarmature winding 178 which supplies current to the power system througha generator breaker when the plant 100 is synchronized and on the line.A transformer 180 supplies a feedback signal for the regulator 170 tocontrol the excitation level of the exciter field 168.

Generally, the rotating rectifier exciter 103 operates without the useof brushes, slip rings, and external connections to the generator field.Brush wear, carbon dust, brush maintenance requirements and brushreplacement are thereby eliminated.

All power required to excite the generator field 176 is delivered fromthe exciter-generator shaft. The only external electrical connection isbetween the stationary exciter field 168 and the excitation switchgear150 (FIG. 1).

All of the exciter parts are supported by the main generator 102. Inparticular, the rotating parts of the exciter 103 are overhung from themain generator shaft to eliminate the need for exciter bearings and tosmooth the operation. The generator rotor can be installed and withdrawnwithout requiring removal of the exciter rotor from the generator shaft.

The brushless excitation system regulator 170 responds to average threephase voltage with frequency insensitivity in determining the excitationlevel of the brushless exciter field 168. If the regulator 170 isdisconnected, a motor operated base adjust rheostat 171 is set by acomputer output signal. The rheostat output is applied through a summingcircuit 173 to a thyristor gate control 175. If the regulator 170 isfunctioning, the base adjust rheostat is left in a preset baseexcitation position, and a motor operated voltage reference adjustrheostat 177 is computer adjusted to provide fine generator voltagecontrol.

An error detector 179 applies an error output to the summing circuit 173as a function of the difference between the computer output referenceand the generator voltage feedback signal. The summing circuit 173 addsthe error signal and the base rheostat signal in generating the outputwhich is coupled to the gate control 175. In the error detector 179, thereference voltage is held substantially constant by the use of atemperature compensated Zener diode. In the gate control 175, solidstate thyristor firing circuitry is employed to produce a gating pulsevariable from 0° to 180° with respect to the voltage supply tothyristors or silicon controlled rectifiers 185.

The silicon controlled rectifiers 185 are connected in an inverterbridge configuration which provides both positive and negative voltagefor forcing the exciter field. However, the exciter field current cannotreverse. Accordingly, the regulator 170 controls the excitation level inthe exciter field 168 and in turn the generator voltage by controllingthe cycle angle at which the silicon controlled rectifiers 185 are madeconductive in each cycle as level of the output from the gate control175.

3. Gas Turbine a. Compressor

The gas turbine 104 in this case is the single shaft simple cycle typehaving a standard ambient pressure ratio of 9.0 to 1 and a rated speedof 4894 rpm and it is illustrated in greater detail in FIG. 5. Filteredinlet air enters a multistage axial flow compressor 181 through aflanged inlet manifold 183 from the inlet ductwork 112. An inlet guidevane assembly 182 includes vanes supported across the compressor inletto provide for surge prevention particularly during startup. The angleat which all of the guide vanes are disposed in relation to the gasstream is uniform and controlled by a pneumatically operated positioningring coupled to the vanes in the inlet guide vane assembly 182.

The compressor 181 is provided with a casing 184 which is split intobase and cover parts along a horizontal plane. The turbine casingstructure including the compressor casing 184 provides support for aturbine rotating element including a compressor rotor 186 throughbearings 188 and 189. Vibration transducers (FIG. 12) similar to thosedescribed in connection with FIG. 4 are provided for the gas turbinebearings 188 and 189.

The compressor casing 184 also supports stationary blades 190 insuccessive stationary blade rows along the air flow path. Further, thecasing 184 operates as a pressure vessel to contain the air flow as itundergoes compression. Bleed flow is obtained under valve control fromintermediate compressor stages to prevent surge during startup.

The compressor inlet air flows annularly through a total of eighteenstages in the compressor 181. Blade 192 mounted on the rotor 186 bymeans of wheels 194 are appropriately designed from an aerodynamic andstructural standpoint for the intended service. A suitable material suchas 12% chrome steel is employed for the rotor blades 192. Both thecompressor inlet and outlet air temperatures are measured by suitablysupported thermocouples (FIG. 12).

b. Combustion System

Pressurized compressor outlet air is directed into a combustion system196 comprising a total of eight combustor baskets 198 conically mountedwithin a section 200 of the casing 184 about the longitudinal axis ofthe gas turbine 104. Combustor shell pressure is detected by a suitablesensor (FIG. 12) coupled to the compressor-combustor flow paths locatedin the pressure switch and gauge cabinet 152.

As schematically illustrated in FIG. 6, the combustor baskets 198 arecross-connected by cross-flame tubes 202 for ignition purposes. Acomputer sequenced ignition system 204 includes igniters 206 and 208associated with respective groups of four combustor baskets 198. In eachbasket group, the combustor baskets 198 are series cross-connected andthe two groups are cross-connected at one end only as indicated by thereference character 210.

Generally, the ignition system 204 includes an ignition transformer andwiring to respective spark plugs which form a part of the igniters 206and 208. The spark plugs are mounted on retractable pistons within theigniters 206 and 208 so that the plugs can be withdrawn from thecombustion zone after ignition has been executed.

A pair of ultraviolet flame detectors 212 are associated with each ofthe end combustor baskets in the respective basket groups in order toverify ignition and continued presence of combustion in the eightcombustor baskets 198. Redundancy in flame sensing capability isespecially desirable because of the hot flame detector environment.

The flame detectors 212 can for example be Edison flame detectors Model424-10433. Generally, the Edison flame detector responds to ultravioletradiation at wavelengths within the range of 1900-2900 Angstroms whichare produced in varying amounts by ordinary combustor flames but not insignificant amounts by other elements of the combustor basketenvironment. Detector pulses are generated, integrated and amplified tooperate a flame relay when a flame is present. Ultraviolet radiationproduces gap voltage breakdown which causes a pulse train. The flamemonitor adds time delay before operating a flame relay if the pulsetrain exceeds the time delay.

In FIG. 7, there is shown a front plan view of a dual fuel nozzlemounted at the compressor end of each combustor basket 198. An oilnozzle 218 is located at the center of the dual nozzle 216 and anatomizing air nozzle 220 is located circumferentially about the oilnozzle 218. An outer gas nozzle 222 is disposed about the atomizing airnozzle 220 to complete the assembly of the fuel nozzle 216.

As indicated in the broken away side view of FIG. 8, fuel oil or otherliquid fuel enters the oil nozzle 218 through a pipe 224 while atomizingair for the fuel oil enters a manifolded pipe arrangement 226 throughentry pipe 228 for flow through the atomizing air nozzle 220. Gaseousfuel is emitted through the nozzle 222 after flow through entry pipe 230and a manifolded pipe arrangement 232.

c. Fuel

Generally, either liquid or gaseous or both liquid and gaseous fuel flowcan be used in the turbine combustion process. Various gaseous fuels canbe burned including gases ranging from blast furnace gas having low BTUcontent to gases with high BTU content such as natural gas, butane orpropane. However, gas with a heat content greater than 500 BTU per scf(LHV) should be burned with the standard combustion system equipmentwhile lower BTU value gases should be used with special techniques inthe fuel handling system and the combustion system.

To prevent condensable liquids in the fuel gas from reaching the nozzles216, suitable traps and heaters can be employed in the fuel supply line.The maximum value of dust content is set at 0.01 grains per standardcubic foot to prevent excess deposit and erosion. Further corrosion isminimized by limiting the fuel gas sulphur content in the form of H₂ Sto a value no greater than 5% (mole percent).

With respect to liquid fuels, the fuel viscosity must be less than 100SSU at the nozzle to assure proper atomization. Most distillates meetthis requirement. However, most crude oils and residual fuels willrequire additive treatment to meet chemical specifications even if theviscosity specification is met. To prevent excess blade deposition,liquid fuel ash content is limited to maximum values of corrosiveconstituents including vanadium, sodium, calcium and sulphur.

A portion of the compressor outlet air flow combines with the fuel ineach combustor basket 198 to produce combustion after ignition and thebalance of the compressor outlet air flow combines with the combustionproducts for flow through the combustor baskets 198 into a multistagereaction type turbine 234 (FIG. 5). The combustor casing section 200 iscoupled to a turbine casing 236 through a vertical casing joint 238. Nohigh pressure air or oil seal is required between the compressor 181 andthe turbine 234.

d. Turbine Element

The turbine 234 is provided with three reaction stages through which themultiple stream combustion system outlet gas flow is directed in anannular flow pattern to transform the kinetic energy of the heated,pressurized gas turbine rotation, i.e. to drive the compressor 181 andthe generator 102. The turbine rotor is formed by a stub shaft 240 andthree disc blade assemblies 240, 242 and 244 mounted on the stub shaftby through bolts. Thermocouples (FIG. 12) are supported within the disccavities to provide cavity temperature signals for the control system.

High temperature alloy rotor blades 246 are mounted on the discs informing the disc assemblies 240, 242 and 244. Individual blade roots arecooled by air extracted from the outlet of the compressor 181 and passedthrough a coolant system in the manner previously indicated. The bladeroots thus serve as a heat sink for the rotating blades 246. Cooling airalso flows over each of the turbine discs to provide a relativelyconstant low metal temperature over the unit operating load range.

The two support bearings 188 and 189 for the turbine rotating structureare journal bearings of the split-shell babbitt lined type. The bearinghousings are external to the casing structure to provide for convenientaccessibility through the inlet and exhaust ends of the structure. Theoverall turbine support structure provides for free expansion andcontraction without disturbance to shaft alignment.

In addition to acting as a pressure containment vessel for the turbine234, the turbine casing 236 supports stationary blades 248 which formthree stationary blade rows interspersed with the rotor blade rows. Gasflow is discharged from the turbine 234 substantially at atmosphericpressure through a flanged exhaust manifold 250 to the outlet ductwork114.

The generator and gas turbine vibration transducers (FIG. 12) can beconventional velocity transducers or pickups which transmit basicvibration signals to a vibration monitor for input to the controlsystem. For example, the Reliance Vibration Monitor Model 2000 can beemployed with three Reliance Model 028F velocity transducers and a CECModel 4-122 High Temperature velocity transducer (for the hot exhaustbearing 189). A pair of conventional speed detectors (FIGS. 12 and 20)are associated with a notched magnetic wheel (FIG. 20) supported atappropriate turbine-generator shaft locations. Signals generated by thespeed detectors are employed in the control system in determining powerplant operation.

Thermocouples (FIG. 12) are associated with the gas turbine bearing oildrains. Further, thermocouples (FIG. 12) for the blade flow path aresupported about the inner periphery of the exhaust manifold 250 toprovide a fast response indication of blade temperature for controlsystem usage particularly during plant startup periods. Exhausttemperature detectors (FIG. 12) are disposed in the exhaust ductwork 114primarily for the purpose of determining average exhaust temperature forcontrol system usage during load operations of the power plant 100.Suitable high response shielded thermocouples for the gas turbine 104are those which use compacted alumina insulation with a thin-wall highalloy swaged sheath or well supported by a separate heavy wall guide.

e. Fuel System

A fuel system 251 is provided for delivering gaseous fuel to the gasnozzles 222 under controlled fuel valve operation as schematicallyillustrated in FIG. 9. Gas is transmitted to a diaphragm operatedpressure regulating valve 54 from the plant gas source. A pressureswitch 255 provides for transfer to oil fuel at a low gas pressurelimit. Pressure switches 257 and 259 provide high and low pressure limitcontrol action on the downstream side of the valve 254. It is noted atthis point in the description that IEEE switchgear device numbers aregenerally used herein where appropriate as incorporated in AmericanStandard C37.2-1956.

A starting valve 256 determines gas fuel flow to the nozzles 222 atturbine speeds up to approximately 10% rated flow, and for this purposeit is pneumatically positioned by an electropneumatic converter 261 inresponse to an electric control signal. At gas flow from 10% to 100%rated, a throttle valve 258 determines gas fuel flow to the nozzles 222under the pneumatic positioning control of an electropneumatic converter263 and a pneumatic pressure booster relay 265. The converter 263 alsoresponds to an electric control signal as subsequently more fullyconsidered.

A pneumatically operated trip valve 260 stops gas fuel flow undermechanical actuation if turbine overspeed reaches a predetermined levelsuch as 110% rated speed. A pneumatically operated vent valve 262 allowstrapped gas to be vented to the atmosphere if the trip valve 260 and anon/off pneumatically operated isolation valve 264 are both closed. Theisolation valve fuel control action is initiated by an electric controlsignal applied through the pressure switch and gauge cabinet 152 (FIG. 1and FIG. 12). A pressure switch 267 indicates fuel pressure at the inletto the nozzles 222.

As schematically shown in FIG. 10, a liquid fuel supply system 266provides for liquid fuel flow to the eight nozzles 218 from the plantsource through piping and various pneumatically operated valves by meansof the pumping action of a turbine shaft driven main fuel pump 268. Pumpdischarge pressure is sensed for control system use by a detector 269. Abypass valve 271 is pneumatically operated by an electropneumaticconverter 270 and a booster relay 272 to determine liquid fuel bypassflow to a return line and thereby regulate liquid fuel dischargepressure. An electric control signal provides for pump dischargepressure control, and in particular it provides for ramp pump dischargepressure control during turbine startup. A throttle valve 272 is held ata minimum position during the ramp pressure control action on thedischarge pressure regulator valve 270. A pressure switch 269 providesfor DC backup pump operation on low pressure, and a pressure switch 271indicates whether the pump 268 has pressurized intake flow.

After pressure ramping, the pneumatically operated throttle valve 272 ispositioned to control liquid fuel flow to the nozzles 218 as determinedby an electropneumatic converter 274 and a booster relay 276. Anelectric control signal determines the converter position control actionfor the throttle valve 272. The bypass valve 270 continues to operate tohold fuel discharge pressure constant.

As in the gas fuel system 251, a mechanically actuated and pneumaticallyoperated overspeed trip valve 278 stops liquid fuel flow in the event ofturbine overspeed. A suitable filter 280 is included in the liquid fuelflow path, and, as in the gas fuel system 251, an electrically actuatedand pneumatically operated isolation valve provides on/off control ofliquid fuel flow to a liquid manifold 283.

Eight positive displacement pumps 284 are respectively disposed in theindividual liquid fuel flow paths to the nozzles 218. The pumps 284 aremounted on a single shaft and they are driven by the oil flow from themanifold 283 to produce substantially equal nozzle fuel flows. Checkvalves 286 prevent back flow from the nozzles 218 and a pressure switch288 indicates fuel pressure at the oil nozzles 218. A manifold drainvalve 290 is pneumatically operated under electric signal control duringturbine shutdown to drain any liquid fuel remaining in the manifold 283.

4. Plant Performance Characteristics

The power plant 100 with the W251G gas turbine 104 provides thefollowing standard performance:

    ______________________________________                                        GAS TURBINE GENERATOR -                                                       STANDARD PERFORMANCE                                                                                Plant                                                                 Plant   Heat                                                    Type Firing   Net     Rate    Nominal Exhaust                                 of   Level    Rating  BTU/KW  Flow    Temperature                             Fuel Mode     KW      Hr      LBS/Hour                                                                              Degrees F.                              ______________________________________                                             Base     26,800  13,150  1,184,000                                                                             872                                     Gas  Peak     30,000  12,770  1,184,000                                                                             936                                          Reserve  31,800  12,600  1,184,000                                                                             967                                          Base     26,100  13,780  1,184,000                                                                             872                                     Oil  Peak     29,250  13,360  1,184,000                                                                             936                                          Reserve  31,000  13,190  1,184,000                                                                             967                                     ______________________________________                                         Ambient conditions of 80° F. temperature and 14.17 psia barometric     pressure (1000 ft.). Performance based on lower heating value of natural      gas or distillate oil fuel. All performance is based on standard inlet an     exhaust (sound level "A") systems.                                       

A similar power plant (not shown) with the higher rated WestinghouseW501-G gas turbines provides the following standard performance:

    ______________________________________                                        GAS TURBINE GENERATOR -                                                       STANDARD PERFORMANCE                                                                                Plant                                                                 Plant   Heat                                                    Type Firing   Net     Rate    Nominal Exhaust                                 of   Level    Rating  BTU/KW  Flow    Temperature                             Fuel Mode     KW      Hr      LBS/Hour                                                                              Degrees F.                              ______________________________________                                             Base     51,780  12,220  2,352,000                                                                             810                                     Gas  Peak     58,000  11,930  2,352,000                                                                             862                                          Reserve  61,480  11,830  2,352,000                                                                             894                                          Base     50,580  12,630  2,352,000                                                                             810                                     Oil  Peak     56,650  12,330  2,352,000                                                                             862                                          Reserve  60,050  12,210  2,352,000                                                                             894                                     ______________________________________                                         Ambient conditions of 80° F. temperature and 14.17 psia barometric     pressure (1000 ft.). Performance based on lower heating value of natural      gas or distillate oil fuel. All performance is based on standard inlet an     exhaust (sound level "A") systems.                                       

With reference again to the gas turbine power plant 100, the followingrated performance data indicates the plant availability for powergeneration:

    ______________________________________                                        Starting Sequence Normal      Fast*                                           ______________________________________                                        Synchronous speed in min.                                                                       8           4.5                                             from ready to start                                                           Warm-up synchronous speed                                                                       0           0                                               Loading time - min.                                                                             2           0.5                                             Total time to rated load-                                                                       10          5                                               min.                                                                          ______________________________________                                         For the NORMAL starting sequence, the loading cycle consists of an            approximately 25% step load followed by a loading rate of 371/2% per          minute.                                                                       *Available with optional oversized diesel staring engine and control          system modification.                                                     

The following data is similarly indicative of plant availability forpower generation for a W501-G plant:

    ______________________________________                                        Starting Sequence                                                                             Normal    Fast    Emergency                                   ______________________________________                                        Synchronous speed in min.                                                                     15        15      8                                           from ready to start                                                           Load acceptance upon                                                                          4         4       4                                           synchronizing, MW                                                             Warm-up at synchronous                                                                        0         0       0                                           speed, min.                                                                   Loading rate, %/min.                                                                          6.6       20      50                                          Loading time, min.                                                                            15        5.0     2.0                                         Total time to rated base                                                                      30        20      10                                          load, min.                                                                    ______________________________________                                    

In FIGS. 11A-11C there are shown respective curves pertaining to thepower generation as a function of fuel consumption and compressor inlettemperature for the power plant 100. The curves in FIGS. 11A-11Crespectively pertain to the base, peak and system reserve levels ofturbine firing operation. The following data pertains to the respectiveFIGS. 11A-11C:

    ______________________________________                                        FIG. 11A                                                                                  Rated (100%) Performance                                                                     Heat Rate                                                  Fuel Ratio                                                                              Power    BTU/KW- Fuel Input                                 Fuel    HHV/LHV   KW       HR LHV  MM BTU/HR                                  ______________________________________                                        Nat. Gas                                                                              1.11      26,800   13,150  352.420                                    Dist. Oil                                                                             1.11      26,100   13,780  359.658                                    Inlet/Exhaust Excess Losses Zero in. H.sub.2 O -                              Elevation 1,000 Ft.                                                           Firing Level Base - Maximum Power 35,000 KW.                                  ______________________________________                                        FIG. 11B                                                                                  Rated (100%) Performance                                                                     Heat Rate                                                  Fuel Ratio                                                                              Power    BTU/KW- Fuel Input                                 Fuel    HHV/LHV   KW       HR LHV  MM BTU/HR                                  ______________________________________                                        Nat. Gas                                                                              1.11      30,000   12,770  383.100                                    Dist. Oil                                                                             1.06      29,250   13,360  383.546                                    Inlet/Exhaust Excess Losses Zero in. H.sub.2 O                                Elevation 1,000 Ft.                                                           Firing Level Peak - Maximum Power 35,000 KW.                                  ______________________________________                                        FIG. 11C                                                                                  Rated (100%) Performance                                                                     Heat Rate                                                  Fuel Ratio                                                                              Power    BTU/KW- Fuel Input                                 Fuel    HHV/LHV   KW       HR LHV  MM BTU/HR                                  ______________________________________                                        Nat. Gas                                                                              1.11      31,800   12,600  400.680                                    Dist. Oil                                                                             1.06      31,000   13,190  408.890                                    Inlet/Exhaust Excess Losses Zero in. H.sub.2 O -                              Elevation 1,000 Ft.                                                           Firing Level Reserve - Maximum Power 35,000 KW.                               ______________________________________                                    

Another typical performance characteristic for the power plant 100 isillustrated in FIG. 11D. The illustrated set of curves shows the mannerin which turbine exhaust temperature is expected to vary as a functionof the ambient temperature at the specified exhaust flow rates. The datapertains to operation at an altitude of 1000 feet, a 100% exhaust flowvalue of 1,184,000 LBS/HR, and a 100% power value of 26,800 KW (naturalgas) or 26,100 KW (distillate gas).

In FIGS. 11E-11G, there are various curves which illustrate theperformance capability of the generator 102. These curves pertain to agenerator rated at 31,765 KVA, 0.85 PF, 27,000 KW, 13.8 KV, 1329 amps,three phase, 60 HZ, 3600 rpm, 0.58 scr, 215 volt excitation, with 104°F. ambient air at 1000 FT. altitude.

B. POWER PLANT OPERATION AND CONTROL 1. General

The power plant 100 is operated under the control of an integratedturbine-generator control system 300 which is schematically illustratedin FIG. 12. In its preferred embodiment, the control system 300 employsanalog and digital computer circuitry to provide reliable hybrid gasturbine and gas turbine power plant control and operation. The plantcontrol system 300 embraces elements disposed in the control cabinet118, the pressure switch and gauge cabinet 152 and other elementsincluded in the electric power plant 100 of FIG. 1. If multiple plantslike the power plant 1000 are to be operated, the control system 300further embraces any additional circuitry needed for the additionalplant operations.

The control system 300 is characterized with centralized systempackaging. Thus, the control cabinet 118 shown in FIG. 1 houses anentire speed/load control package, an automatic plant sequencer package,and a systems monitoring package. As previously considered, up to fourturbine generator plants can be operated by the centralized controlsystem 300 and such operation is provided with the use of a singlecomputer main frame. A second control cabinet is required if two orthree plants are controlled and a third control cabinet is required iffour plants are placed under controlled operation as previouslyconsidered in connection with FIG. 1. Generally, the control cabinetpackage is factory prewired and it and field interconnecting cables arecompletely checked and calibrated at the factory.

As a further benefit to the plant operator, turbine and generatoroperating functions are included on a single operator's panel inconformity with the integrated turbine-generator plant control providedby the control system 300. Final field calibration is facilitated bycalibration functions for control system variables which can beselectively displayed on the operator's panel. System troubleshooting isfacilitated by maintenance functions provided on the operator's panel.

The control system 300 provides automatically, reliably and efficientlysequenced start-stop plant operation, monitoring and alarm functions forplant protection and accurately, reliably and efficiently performingspeed/load control during plant startup, running operation and shutdown.The plant operator can selectively advance the turbine start cyclethrough discrete steps by manual operation and, more generally, canobtain a wide variety of plant management benefits through theoperator/control system interfaces subsequently considered more fully.

Under automatic control, the power plant 100 can be operated under localoperator control or it can be unattended and operated by direct wiredremote or supervisory control. Further, the plant 100 is started fromrest, accelerated under accurate and efficient control to synchronousspeed preferably in a normal fixed time period to achieve in the generalcase extended time between turbine repairs, synchronized manually orautomatically with the power system and loaded under preferred rampcontrol to a preselectable constant or temperature limit controlled loadlevel thereby providing better power plant management.

In order to start the plant 100, the control system 300 first requirescertain status information generated by operator switches, temperaturemeasurements, pressure switches and other sensor devices. Once it islogically determined that the overall plant status is satisfactory, theplant startup is initiated under programmed computer control. Plantdevices are started in parallel whenever possible to increase plantavailability for power generation purposes. Under program control,completion of one sequence step generally initiates the next sequencestep unless a shutdown alarm occurs. Plant availability is furtheradvanced by startup sequencing which provides for multiple ignitionattempts in the event of ignition failure.

The starting sequence generally embraces starting the plant lubricationoil pumps, starting the turning gear, starting and operating thestarting engine to accelerate the gas turbine 104 from low speed,stopping the turning gear, igniting the fuel in the combustion system atabout 20% speed, accelerating the gas turbine to about 60% speed andstopping the starting engine, accelerating the gas turbine 104 tosynchronous speed, and loading the power after the generator breakerclosure. During shutdown, fuel flow is stopped and the gas turbine 104undergoes a deceleration coastdown. The turning gear is started to drivethe turbine rotating element during the cooling off period.

2. Control Loop Arrangement-Without Hardware/Software Definition

A control loop arrangement 302 shown in FIG. 13A provides arepresentation of the preferred general control looping embodied in thepreferred control system and applicable in a wide variety of otherapplications of the invention. Protection, sequencing, more detailedcontrol functioning and other aspects of the control system operationare subsequently considered more fully herein. In FIGS. 13A-D, SAMAstandard function symbols are employed.

The control loop arrangement 302 comprises an arrangement of blocks inthe preferred configuration of process control loops for use inoperating the gas turbine power plant 100 or other industrial gasturbine apparatus. No delineation is made in FIG. 13A between hardwareand software elements since many aspects of the control philosophy canbe implemented in hard or soft form. However, it is noteworthy thatvarious advantages are gained by hybrid software/hardware implementationof the control arrangement 302 and preferably by implementation in thehybrid form represented by the control system 300.

Generally, a feedforward characterization is preferably used todetermine a representation of fuel demand needed to satisfy speedrequirements. Measured process variables including turbine speed, thecontrolled load variable or the plant megawatts, combustor shellpressure and turbine exhaust temperature are employed to limit,calibrate or control the fuel demand so that apparatus design limits arenot exceeded. The characterization of the feedforward speed fuel demand,a surge limit fuel demand and a temperature limit fuel demand arepreferably nonlinear in accordance with the nonlinear characteristics ofthe gas turbine to achieve more accurate, more efficient, more availableand more reliable gas turbine apparatus operation. The controlarrangement 302 has capability for maintaining cycle temperature, gasturbine apparatus speed, acceleration rate during startup, loading rateand compressor surge margin.

The fuel demand in the control arrangement 302 provides position controlfor turbine gas or liquid fuel valves. Further, the control arrangement302 can provide for simultaneous burning of gas and liquid fuel and itcan provide for automatic bumpless transfer from one fuel to the otherwhen required. The subject of bumpless plant transfer between differentfuels and the plant operation associated therewith is disclosed in thepreviously noted. fuel transfer copending patent application now U.S.Pat. No. 3,919,623.

Generally, the control arrangement 302 involves little risk of exceedinggas turbine design temperature limits. This reliability stems from theparticular process variables from which fuel demand is determined andthe manner in which the fuel demand is determined from the variables.

During startup and after ignition, a feedforward loop 304 provides arepresentation of a speed reference from a nonlinear predeterminedconstant turbine inlet temperature characterization 306 (normal) or 307(emergency) to the input of a feedback control loop 308 where it issummed with a measured turbine speed representation in block 310. Avariable speed regulation of 2l% to 6% is applied in block 312 and aproportional plus rate amplifier block 314 generates a speed fuel demandrepresentation.

Preferably, the operation of the loops 304 and 308 normally provide forturbine acceleration in a fixed interval of time as determined from asuitable and preferably nonlinear characterization such as that shown inFIG. 14. The fixed acceleration time period is maintained regardless ofcompressor inlet air temperature, fuel supply pressure, fuel heatingvalue and cycle component efficiencies.

With constant acceleration time between ignition and synchronism, thetime interim between gas turbine overhauls is extended. Thus, whenoperation occurs in periods with reduced ambient and compressor inletair temperature, a reduced turbine inlet temperature and reduced turbinetemperature transients occur with the normally fixed acceleration timeperiod. Reduced cycle temperature would occur for example during coldweather operation or where compressor inlet air cooling is employed.

In the combination of plural control loop functions in the arrangement302, a low fuel demand selector block 316 is preferably employed tolimit the speed reference fuel demand representation if any of threelimit representations are exceeded by it during startup. These limitrepresentations are generated respectively by a surge control 318, ablade path temperature control 320, and an exhaust temperature control322. In this application, a load control block 324 becomes operativeafter synchronization with the limit blocks 318, 320 and 322.

The surge control 318 includes a characterization block 325 whichresponds to sensed combustion shell pressure and compressor inlettemperature to generate the surge limit representation for compressorsurge prevention as illustrated in FIG. 13B. The characterizationprovided by the block 325 is preferably nonlinear, i.e.characterizations represented in FIG. 15 are employed. The curve 326limits startup fuel demand for an ambient temperature of 120° F. and thecurve 328 limits startup fuel demand for an ambient temperature of -40°F. Common curve portions 330 are operative at various ambienttemperatures to provide a substantially linear surge limit during loadoperations.

As shown in FIG. 13C, the blade path temperature control 320 includes ablock 332 which responds to combustor shell pressure in accordance witha first preferably nonlinear temperature reference characteristic 334for normal startup and a second preferably nonlinear temperaturereference characteristic 336 for emergency startup as illustrated inFIG. 16. The exhaust temperature control 322 includes a block 338 whichresponds to combustor shell pressure in accordance with a firstpreferably nonlinear temperature reference characteristic 340 for baseload operation, a second preferably nonlinear temperature referencecharacteristic 342 for peak load operation and a third preferablynonlinear temperature reference characteristic 344 for system reserveload operation as shown in FIG. 17. The startup curves 334 and 336correspond respectively to 1200° F. and 1500° F. turbine inlettemperature while the load curves correspond to respectively highervalues of turbine inlet temperature operation.

In this case, a transfer block 346 (FIG. 13C) selects the exhausttemperature reference for further processing in an exhaust temperaturecutback and tracking control clock 347 during load operations if block348 generates a representation that the generator breaker is closed.Otherwise the transfer block 346 selects the blade path temperaturereference for further processing in a blade temperature cutback andtracking control block 349 during startup or isolated plant operations.The block 349 is identical with the block 347 except that the block 349uses eight blade path thermocouples in place of eight exhaustthermocouples used in the block 347. During startup, an inhibit block351 preferably prevents the low fuel demand selector 316 from respondingto the exhaust temperature control block 322 because a reliable averageexhaust temperatuare ordinarily is not available during most of thestartup transient.

As shown in FIG. 13C, the block 347 or 349 in this instance includes apair of groups of four thermocouples which are coupled process blocks353 and 355 in separate channels where the following processing isperformed:

1. Linearization

2. Open circuit test and alarm

3. Short circuit test and alarm

4. High error and absolute limits and alarm

5. Bad input rejection

In the preferred control system 300, computer program operationssubsequently considered more fully provide the described thermocoupledata processing.

Block 357 next selects the highest of the two average temperaturesdetermined for the two thermocouple groups in accordance with thefollowing formula:

    T.sub.AV =Σ/NT.sub.N

where:

T_(AV) =average temperature

N=valid inputs to be averaged.

An error between the temperature reference selected by the transferblock 346 and the output from the high thermocouple select block 357 isgenerated by a difference block 359.

When the temperature error representation is positive, a zero isgenerated by low selector block 360 so that a proportional controller362 generates no outputs. To prevent integral windup of a resetcontroller 370, difference block 365 in this case applies the positiveerror representation to transfer block 368 to cause the reset controller370 to generate an output representation which tracks the outputrepresentation of the low fuel demand selector 316. In this manner, theinput temperature limit representation to the fuel demand selector 316from the blade path temperature block 320 or the exhaust temperatureblock 322 through block 372 is always at or close to a value which needsonly to be decremented to produce temperature limit control action inthe event the temperature error sign changes from positive to negative.To provide for the tracking operation, the output of the resetcontroller 370 is applied to an input difference block 374 along with arepresentation of the output fuel demand representation from the fueldemand selector 316. A bias is summed with the resultant error signal byblock 376 to cause the reset controller output to exceed the fuel demandsignal slightly thereby providing some + and - control range for theselector input control which is driving the selector 316.

If the temperature error at the output of the difference block 359 isnegative, the reset controller 370 is switched from its trackingoperation by transfer block 368 through the routing of a zerorepresentation to reset controller summer input block 369 through thetransfer block 368. Further, the negative temperature error signal isthen selected by the low select block 360 for application to the inputof the proportional controller 362 and the reset controller 370 throughthe summer block 369. For negative temperature error, the blocks 362 and370 thus form a proportional plus reset controller having their outputssummed in block 372 for application to the low fuel demand selector 316.In the preferred control system 300, it is noteworthy that rate actionis also provided in the temperature control channels as considered morefully subsequently.

A negative temperature error is alarmed through block 378 to causeturbine shutdown if the temperature error is more than a predeterminedamount. A deadband is provided in the block 378 to prevent alarms forsmall temperature errors.

After the generator 102 has been synchronized with the line with the useof the preferred control system 300, the gas turbine speed is regulatedby the system frequency if the power system is large and the speedreference applied to the difference block 310 in FIG. 13A is set at ahigher value such as 106%. The speed fuel demand signal applied to theinput of the fuel demand selector 316 thus is normally much higher thanother inputs to the selector 316 during system load operation. If thegenerator 102 is separated from the power system for isolated operation,the turbine 104 is controlled to operate at the 106% speed reference.

The load control block 324 becomes operative during load operation ofthe gas turbine power plant 100. A feedforward control embodiment of itis shown in greater schematic detail in FIG. 13D. A feedback controlembodiment is employed in the preferred control system 300 assubsequently described. More particularly, the load control block 324 inFIG. 13D includes a kilowatt reference block 380 which generates areference representation applied to a feedforward characterization block382 through a summer block 384 to which a bias is applied. Thecharacterized output kilowatt reference representation is applied to asummer block 386 where a calibration summation is made with the outputfrom a reset controller 388. The output from the summer block 386defines the corrected load fuel demand limit for application to the lowfuel demand selector 316 through a transfer block 389. In startup, thetransfer block 389 causes a high value to be applied to the low demandselector 316 so that the load control is nonlimiting.

For mode 3 fixed or constant load control, transfer block 390 enablesthe reset controller 388 to integrate any error between actual generatorkilowatts and the kilowatt reference representation from the block 380as determined in difference block 392 to provide a trim correction tothe sum block 386. Under turbine temperature load limit operation, anerror between the output of block 386 and the fuel demand signal isgenerated by block 387 and applied to the input of the reset controller388 by the transfer block 390 to obtain tracking action (with bias ifdesired) for reasons like those considered previously in connection withtemperature limit control. In the temperature load limit case, thetemperature control limit imposed preferably by the exhaust temperaturecontrol 322 prevent overloading of the turbine-generator and in so doingprovides load control by limit action.

Fixed load operation is referred to as Mode 3 and it occurs after thegenerator and line breakers are closed if minimum load is selected andif fixed load control is included in the control package and selectedfor operation. In Mode 3 a kilowatt limit is accordingly imposed on thelow fuel demand selector 316 in addition to the previously describedlimits. At minimum load operation, the kilowatt reference representationis fixed and, in the FIG. 13D embodiment, feedforward control action isdeveloped as just described. On base, peak or system reserve operationin Mode 4, the reference representation generated in FIG. 13D by theblock 380 is preferably ramped to the maximum value causing thetemperature control to take over and control the load by exhaust orblade path temperature limit.

In the preferred control system 300, a load rate of 50% per minute isprovided. Under selectable emergency start, a faster load rate can beprovided. Operator raise and lower pushbuttons can also be employed forload control, and when so used they increment or decrement the kilowattreference representation. For pushbutton operation, the increment rateis 50% load per minute and the decrement rate is 100% per 30 to 40seconds per NEMA specifications.

At the output of the low fuel demand selector 316, the fuel demandrepresentation is applied to a dual fuel control where the fuel demandsignal is processed to produce a gas fuel demand signal for applicationto the gas starting and throttle valves or a liquid fuel demand signalfor application to the oil throttle and pressure bypass valve or as acombination of gas and liquid fuel demand signals for application to thegas and oil valves together.

To generate a speed reference representation in Mode 1, the followingalgorithm is employed in the preferred control system 300:

    W.sub.R(t) =W.sub.R(t-Δt) +a.sub.(t-Δt) Δt

where:

a=fn(W_(R)) for normal acceleration (derived from FIG. 14)

a=fe(W_(R)) for emergency acceleration (derived from FIG. 14)

W_(R) =speed reference

    W.sub.MIN ≦W.sub.R ≦W.sub.SYNCH

W_(R)(c) =initial speed value.

To compute a load demand representation, the following algorithm may beemployed: ##EQU1## where:

D_(R) =load reference

T_(D) =repeats/second required for fixed time to reach desired load

D_(R) (O)=Initial load value.

To determine the fuel demand representation the following algorithms maybe employed:

Q_(FW) =(W_(R) -W) K for speed

Q_(FD) =KD_(R) +1/S (D_(R) -D) for load with load conrol or

Q_(FD) =KD_(R) without load control.

The algorithms implemented in the preferred control system 300 are morefully described subsequently.

In addition to Mode 3 and Mode 4, the control modes of operation asdefined herein further include Mode 0, Mode 1, and Mode 2. Mode 0 is thepre-ignition mode which applies to the startup period up toapproximately 20% speed. During Mode 0 operation, plant statusinformation is determined by the control system 300 for sequencing andprotection purposes.

Reference is made to FIG. 18 where there is shown a schematic diagramrepresentative of the events involved in gas turbine startup embraced byoperating Modes 0, 1 and 2 in the preferred embodiment. FIG. 18 alsoillustrates the sequencing involved in shutdown.

After ignition, the control loops are automatically transferred to Mode1 by sequencing operations. The speed fuel demand reference W_(R) isthen increased as previously considered in connection with FIG. 14 for anormal or an emergency start. In addition, the surge control limit andtemperature cutback control action are provided as already considered.

During Mode 2 sequence operations transfer the control forsynchronization which can be performed manually or automatically. Thesubject matter of automatic synchronization and its relationship topower plant operations is disclosed in the previously identified Reutherand Reed copending applications W. E. 40,218 and WIS 70-01. Theprocedure for manual synchronization is subsequently considered morefully herein. As in the case of Mode 0 operation, sequence andprotection operations are interfaced with the control loops during Mode1 and 2 operations as generally indicated in FIG. 18.

The control arrangement 302 generally protects gas turbine apparatusagainst factors including too high loading rates, too high speedexcursions during load transients, too high fuel flow which may resultin overload too low fuel flow which may result in combustor systemoutfires during all defined modes of operation, compressor surge, andexcessive turbine inlet exhaust and blade over-temperature. Further, thecontrol arrangement 302 as embodied in the control system 300 meets allrequirements set forth in the NEMA publication "Gas Turbine Governors",SM32-1960 relative to system stability and transient response andadjustment capability.

3. Control System

The control system 300 is shown in block diagram detail in FIG. 12. Itincludes a general purpose digital computer system comprising a centralprocessor 304 and associated input/output interfacing equipment such asthat sold by Westinghouse Electric Corporation under the trade namePRODAC 50 (P50). Generally, the P50 computer system employs a 16,000word core memory with a word length of 14 bits and a 4.5 microsecondcycle time. The P50 is capable of handling a large volume of data andinstructions so as readily to provide for handling the tasks associatedwith controlling and operating multiple gas turbine plant units asgenerally considered previously and as more fully consideredsubsequently.

The P50 core memory is expandable, and by addition of functional modularunits the P50 is capable of substantial increase in its analog unitcapacity, contact closure inputs, and contact closure outputs. Datacommunication is provided for the P50 by 64 input and output channels,each of which provides a 14 bit parallel path into or out of thecomputer main frame. The P50 addressing capability permits selection ofany of the 64 input/output channels, any of the 64 word addresses foreach channel and any of the 14 bits in each word. Over 50,000 points ina process can thus be reached individually by the P50 computer system.

More specifically, the interfacing equipment for the computer 304includes a contact closure input system 306 which scans contact or othersimilar signals representing the status of various plant and equipmentconditions. The status contacts might typically be contacts of mercurywetted relays (not shown) which are operated by energization circuits(not shown) capable of sensing the predetermined conditions associatedwith the various plant devices. Status contact data is used for examplein interlock logic functioning in control and sequence programs,protection and alarm system functioning, and programmed monitoring andlogging.

Input interfacing is also provided for the computer 304 by aconventional analog input system 308 which samples analog signals fromthe gas turbine power plant 100 at a predetermined rate such as 30points per second for each analog channel input and converts the signalsamples to digital values for computer entry. A conventionalteletypewriter system or printer 310 is also included and it is used forpurposes including for example logging printouts as indicated by thereference character 312.

A conventional interrupt system 314 is provided with suitable hardwareand circuitry for controlling the input and output transfer ofinformation between the computer processor 304 and the slowerinput/output equipment. Thus, an interrupt signal is applied to theprocessor 304 when an input is ready for entry or when an outputtransfer has been completed. In general, the central processor 304 actson interrupts in accordance with a conventional executive programconsidered in more detail hereinafter. In some cases, particularinterrupts are acknowledged and operated upon without executive prioritylimitations. There are up to 64 independent available for the centralprocessor 304 in the P50 computer system. Each of the employed interruptinputs causes a separate and unique response within the computer mainframe without need for additional input operations thereby allowing theprocessing of interrupt input signals with very little main frame dutycycle.

Output interfacing generally is provided for the comuter by means of aconventional contact closure output system 316. Analog outputs aretransmitted through the contact closure output system 316 under programcontrol as subsequently considered more fully.

The plant battery 132 considered previously in connection with FIG. 1 isalso illustrated in FIG. 12 since it provides for operating an inverter318 which provides the power necessary for operating the computersystem, control system and other elements in the power plant 100. Theinverter 318 can be an equipment item sold by Solidstate Controls, Inc.and identified as Model No. W-CR-267-DCA. Battery charging is providedby a suitable charger 320.

The contact closure input system 306 is coupled by cabled wire pairs tothe operator's console panel 120, considered previously in connectionwith FIG. 1, and to a remote operator's panel 322. As shown in FIG. 12,connections are also made to the contact closure input system 306 fromthe inverter 318 and the battery charger 320 and various turbine,protective relay, switchgear, pressure switch and gauge cabinet, andstarting engine contacts. In addition certain customer selected contactsand miscellaneous contacts such as those in the motor control center 130(FIG. 1) are coupled to the contact closure input system 306.

In FIGS. 19A and 19B there is schematically illustrated a cablingdiagram generally corresponding to the block diagram shown in FIG. 12.However, the central processor 304 and associated computer systemequipment shown in FIG. 12 are grouped together as a single computersystem block 305 in FIGS. 19A and 19B. In addition, a recorder panel307, a supervisory control 309 and an annunciator panel 311 are shown inFIGS. 19A and 19B as options.

Generally, FIG. 19A shows the cabling needed for control systeminterfacing with a first gas turbine power plant designated by theletter "A", and FIG. 19B shows the cabling needed for interfacing thecontrol system with a second gas turbine power plant designated by theletter "B". As already indicated, a total of four gas turbine powerplants can be operated by the P50 computer system and additional cablingdiagrams similar to FIG. 19B are provided when needed for the other twogas turbine plants C and D.

Each line connection in FIG. 19A and FIG. 19B includes a designationwhich identifies the mnemonic, the cable size and the type of couplingor function. For example, the designation for the topmost turbineconnection in FIG. 19A indicates that its identification is A21 and thatthere is one four-wire pair cable used for at least one speed feedbacksignal. Contact closure inputs associated with the contact closure inputsystem 306 in FIG. 12 are represented by the symbol CCI on the lineconnections in FIGS. 19A and 19B. The symbol CCO refers to contactclosure outputs and the symbol AI refers to analog inputs.

The P50 analog input system 308 has applied to it the outputs fromvarious plant process sensors or detectors, many of which have alreadybeen briefly considered. Various analog signals are generated by sensorsassociated with the gas turbine 104 for input to the computer system 305where they are processed for various purposes. The turbine sensorsinclude eight blade path thermocouples, eight disc cavity thermocouples,eight exhaust manifold thermocouples, eight bearing thermocouples,compressor inlet and discharge thermocouples, and, as designated by theblock marked miscellaneous sensors, two oil reservoir thermocouples, abearing oil thermocouple, a control room temperature thermocouple, and amain fuel inlet thermocouple.

A combustor shell pressure sensor and a main speed sensor and a backupspeed sensor also have their output signals coupled to the analog inputsystem 308. The speed sensor outputs are coupled to the analog inputsystem 308 through an analog speed control 324 and an auxiliary speedlimiter 326, respectively. A speed reference signal and a speed/loadlimit signal generated as outputs by the computer 304 and a fuel demandsignal developed by the analog speed control 324 are all coupled to theanalog input system 308 from the analog speed control 324. A turbinesupport metal thermocouple is included in the miscellaneous block.

Sensors associated with the generator 102 and the plant switchgear arealso coupled to the computer 304. The generator temperature sensorsinclude six stator resistance temperature detectors, an inlet airthermocouple, an outlet air thermocouple, and two bearing drainthermocouples. Vibration sensors associated with the generator 102 andthe gas turbine 104 are coupled with the analog input system 308 throughthe operator's console 120 where the rotating equipment vibration can bemonitored. As indicated by the blocks in FIG. 12, additional sensorswhich are located in the protective relay cabinet generate signalsrepresentative of various bus, line, generator and exciter electricalconditions. The operator's panel 120 also generates analog inputsincluding five calibration input connections as indicated by thereference character 328.

Various computer output signals are generated for operating meters atthe operator's console 120 (or for operating recorders which areoptional as shown in FIG. 19A) and they are applied as computer analoginputs as indicated by the reference character 330. Each instrumentoutput circuit included in an instrument output block 331 comprises anintegrating amplifier which operates in a manner like that describedsubsequently in connection with the analog output integrating amplifieremployed for converting the computer digital speed reference output toan analog signal value.

With respect to computer output operations, the contact closure outputsystem 316 transfers digital speed reference, speed/load limit and fueltransfer outputs to external circuitry as indicated respectively by thereference characters 332, 334 and 336. The coupling of the contactclosure output system 316 with the analog speed control 324 is withinthe framework of the preferred software/hardware hybrid control system.Another contact closure output 338 to the analog speed control 324provides for a minimum fuel flow into the turbine combustor system inorder to prevent flameout after ignition.

An analog dual fuel control system 337 is operated by the speed control324 to determine the position of the liquid and gas fuel valvesconsidered in connection with FIGS. 9 and 10. A contact closure outputcoupling to the dual fuel control 337 provides for transfer betweenfuels or relative fuel settings for two fuel or single fuel operation asindicated by the reference character 336. A guide vane control circuit338 is also operated by the speed control 324 to control the position ofthe guide vanes through a guide vane electropneumatic converter 340which actuates the positioning mechanism.

The contact closure output system 316 is also connected to theoperator's panel 120 and to sequence the starting engine 126. Asynchronizer detection circuit 342 has bus, line and generator potentialtransformers coupled to its input and the contact closure output system316 signal provides a visual panel indication for manualsynchronization. The detection circuit 342 also applies signals to theanalog input system 308 for automatic synchronization when suchsynchronization is employed as considered more fully in theaforementioned Reuther and Reed copending patent applications.

Other devices operated by contact closure outputs include the generatorfield breaker and the generator and line breakers 132 and 137. The motoroperated generator exciter field rheostats 171 and 177 and variousdevices in the motor control center 130 and the pressure switch andgauge cabinet 152 also function in response to contact closure outputs.The printer or teletype 310 is operated directly in a specialinput/output channel to the main frame 304.

Pressure Switch and Gauge Cabinet Equipment List

The following items are located in the pressure switch and gauge cabinetand include devices for interconnection with the gas turbine 104 and forinterfacing with the computer control system:

    ______________________________________                                        Item   Description                                                            ______________________________________                                        65     EMERGENCY STOP BUTTON                                                         CAT. OT1D2C DPDT RED                                                          MUSHROOM HEAD                                                                 LEGEND: EMERG.-STOP                                                    66     SAFE RUN SWITCH                                                               CAT. OT1S3C 3 POSITION                                                        SELECTOR, DPDT                                                                LEGEND: TG. - SAFE - TRB TG.                                           67     IGNITION SWITCH                                                               CAT. OT1S3C 3 POSITION                                                        SELECTOR, DPDT                                                                LEGEND: MAN - OFF - AUTO                                               68     INSTRUMENT AIR SOL 20/35 SWITCH                                               CAT. OT1S3C 3 POSITION                                                        SELECTOR DPDT                                                                 LEGEND: MAN - OFF - AUTO                                               69     GAS ISOLATION SWITCH                                                          CAT. OT1S3C 3 POSITION                                                        SELECTOR DPDT                                                                 SELECTOR: MAN - OFF - AUTO                                             70     OIL ISOLATION SWITCH                                                          CAT. OT1S3C 3 POSITION                                                        SELECTOR DPDT                                                                 LEGEND: MAN - OFF - AUTO                                               71     OVER SPEED TRIP SWITCH                                                        CAT. OT1S3C 3 POSITION                                                        SELECTOR DPDT                                                                 LEGEND: MAN - OFF - RESET                                              63-8-1 COMPRESSOR BLEED VALVE                                                        ACT PRESS SWITCH (HP) RANGE 5                                          63-8-2 COMPRESSOR BLEED                                                              VALVE ACT PRESS. SW. (LP)                                                     RANGE 5                                                                63-111 INSTRUMENT AIR                                                                COMPRESSOR PRESS SWITCH                                                       RANGE 7                                                                63-10  COMPRESSOR INLET                                                              PRESS SWITCH                                                                  RANGE 1-30"                                                            63-7   OVERSPEED TRIP                                                                PRESSURE SWITCH                                                               RANGE 5                                                                63-11  INSTRUMENT AIR                                                                PRESS SWITCH                                                                  RANGE 7                                                                63-4   BEARING OIL                                                                   PRESS SWITCH                                                                  RANGE 3A                                                               63-1   BEARING OIL                                                                   PRESS SWITCH                                                                  RANGE 3A                                                               63-3   HIGH PRESS                                                                    OIL SWITCH                                                                    RANGE 5                                                                20-10-1                                                                              3 WAY COMP BLEED VALVE                                                        ACT AIR (HP) SOLENOID VALVE                                            20-10-2                                                                              3 WAY COMP BLEED VALVE                                                        ACT AIR (LP) SOLENOID VALVE                                            20-25  2 WAY COMBUSTOR SIGNAL                                                        LINE BLOWDOWN SOLENOID VALVE                                           20-35  3 WAY INSTRUMENT AIR ISOL.                                                    VALVE SOLENOID VALVE                                                   SC1    E/P SIGNAL CONVERTER                                                          INLET GUIDE VAINE                                                             1 to 5 VOLTS = 6 to 30 PSIG                                            SC2    P/E SIGNAL CONVERTER                                                          COMBUSTOR SHELL PRESSURE                                                      0 to 160 PSIG = 1 to 5 VOLTS                                           PCV-4  INSTRUMENT AIR COMPRESSOR                                                     REGULATOR, RANGE 0-100 PSI                                                    GAGE FOR PIPE MTG.                                                     PCV-3  AIR DRYER OUTLET REGULATOR                                                    RANGE 0-50 PSI                                                                GAGE FOR PIPE MTG.                                                     PCV-28 AIR DRYER OUTLET REGULATOR                                                    RANGE 0-50 PSI                                                                GAGE FOR PIPE MTG.                                                     PCV-50 TRANSDUCER SUPPLY                                                             REGULATOR, RANGE 0-50 PSI                                                     GAGE FOR PIPE MTG.                                                     PCV-51 COMPRESSOR BLEED VALVE                                                        ACT AIR REGULATOR                                                             RANGE 0-100 PSI                                                               GAGE FOR PIPE MTG.                                                     PCV-22 TURB. INSTR. AIR REGULATOR                                                    RANGE 0-50 PSI                                                                GAUGE FOR PIPE MTG.                                                    F1     INSTRUMENT AIR FILTER                                                  F2     COMBUSTOR SHELL AIR FILTER                                             PI-34  41/2" INSTRUMENT AIR SUPPLY                                                   PRESS. GAUGE, 1379A                                                           RANGE 0-160 PSIG - BOTTOM CONN.                                        PI-35  41/2" OVERSPEED TRIP PRESS                                                    GAUGE, 1379B,                                                                 RANGE 0-60 PSIG                                                               BOTTOM CONN.                                                           PI-36  41/2" BEARING OIL PRESS                                                       GAUGE, 1377B,                                                                 RANGE 0-30 PSIG                                                        PI-37  41/2" COMBUSTOR SHELL                                                         PRESSURE GAUGE 1377A                                                          RANGE 0-169 PSIG                                                       CV-1   CHECK VALVE, 1/2"                                                      CV-2   CHECK VALVE, 1/2"                                                      63-21  ATOMIZING AIR TANK                                                            PRESS SWITCH RANGE 9                                                   63-9DT FUEL SUPPLY PRESS.                                                            SWITCH, RANGE 4                                                        20-2B  3 WAY MANIFOLD DRAIN SOLENOID VALVE                                    63-962 GAS ISOL. VALVE ACT. AIR                                                      PRESS. SWITCH RANGE 4                                                  63-9DS MAIN FUEL PUMP INLET                                                          PRESS SWITCH, RANGE 263                                                20-17  3 WAY ATOMIZING AIR ISOLATION                                                 VALVE SOLENOID VALVE                                                   20-1D  3 WAY FUEL OIL ISOLATION                                                      VALVE SOLENOID VALVE                                                   20-1G  3 WAY FUEL GAS ISOLATION                                                      VALVE SOLENOID VALVE                                                   30-3B  3 WAY GAS VENT VALVE                                                          SOLENOID VALVE                                                         SC-3   P/E SIGNAL CONVERTER                                                          FUEL PUMP DISCHARGE                                                           0-1000 PSIG = 1-5 VOLTS                                                PI-33  41/2" INLET GUID VANE PRESS                                                   GAUGE, 1379B, RANGE 0- 60 PSIG                                                BOTTOM CONN.                                                           PI-61  41/2" ATOMIZING AIR PRESS                                                     GAUGE, 1379A, RANGE 0-160 PSIG                                                BOTTOM CONN.                                                           PI-63  41/2" FUEL DISTRIBUTION                                                       INLET PRESS GAUGE 1377S                                                       RANGE 0-1000 PSIG                                                      PI-64  41/2" FUEL PUMP DISCHARGE                                                     PRESS GAUGE 1377 - TAS                                                        RANGE 0-1500 PSIG                                                      74     MOUNTING PLATE ASSY. FOR 12 -                                                 56 POINT ELCO CONNECTORS                                               79     36 POINT ELECTRICAL TERM BLOCK                                         81     15 PT. TERMINAL BLOCK                                                  82     DIODES, 1000V, 1 AMP.                                                         (SEM TECH. CORP. MODEL SC-10)                                          AC-84  150 CU. IN. ACCUMULATOR VOLUME                                         86     MG-6-RELAY                                                             87     MG-6-RELAY                                                             88     MG-6-RELAY                                                             89     MG-6-RELAY                                                             90     24 PT. ELECTRICAL BLOCK                                                91     MG-6-RELAY                                                             92     VIBRATION DAMPENER                                                     96     MG-6-RELAY                                                             ______________________________________                                    

Analog Circuitry

The speed control circuit 324 operates in response to a main speedgenerated by a main turbine speed sensor 344 associated with a 44 toothmagnetic rotor wheel 345 as shown in greater detail in FIG. 20. Thespeed sensor 344 is a conventional reluctance type device whichgenerates a sinusoidal output waveform. Circuit block 346 converts thesinusoidal speed signal into an output signal having a constant widthpulse at twice the input frequency.

Generally, the circuit block 346 includes a zero crossing senseamplifier which produces a pulse of approximately 15 microsecondsduration every time the input waveform crosses zero. To detect zerocrossing, to the block 346 the input is compared with zero by a twostage comparator which changes state every time the input crosses zero.The edges of the comparator square wave output are differentiated toproduce a pulse train having twice the input frequency. In turn, theresultant output pulse train is applied to counter enable circuitrywhich initiates the operation of a clocked counter on the occurrence ofeach pulse. The counter enable circuitry is reset by the clocked counter85 microseconds after the application of each set pulse. Accordingly, acircuit block output is generated by the counter enable circuitry in theform of a train of 85 microsecond pulses occurring at twice the inputfrequency.

The output pulse train from the circuit block 346 is applied to circuitblock 348 which converts the pulse train into a direct voltageproportional to the pulse frequency. Generally, the circuit block 348comprises a transistor switch network which is coupled to an R-Caveraging network. The ON time of the transistor switch network is aconstant 85 microseconds but the OFF time varies inversely with theinput frequency. The averaging network generates a DC voltage outputwhich is amplified and it is a function of the relationship between theON and OFF times of the transistor switch network. Accordingly, theamplitude of the averaging network output is directly proportional tothe frequency of the input constant width pulse train.

From the circuit block 348, an output is applied to a turbine speedmeter 349 and to the input of an error detector circuit block 350. It isnoted at this point in the description that each circuit block in FIG.20 denotes a circuit card which is mounted in the control cabinet.

The actual speed signal at the output of the circuit block 348 is alsoapplied to the analog input system 308 (FIG. 12). The computer therebyobtains a representation of the actual turbine speed determined by themain turbine speed sensor 344.

At the input of the speed error detector circuit 350, the speed signalis amplified and inverted by an operational amplifier 352. It is thenapplied to the input summing junction of an error detector operationalamplifier 354.

A speed reference signal as indicated by the reference 356 and anadjustable speed regulation feedback signal indicated by the referencecharacter 358 are also applied to the error detector summing junction.An adjustable potentiometer 360 determines the gain of the amplifier 354by determining the magnitude of the amplifier circuit feedback signal,and the potentiometer resistance variation provides for adjustment inthe gain and the speed regulation over a range from 2% to 6%.

The speed reference signal is an analog signal obtained from an analogoutput circuit block 362 which operates as a digital to analog converterin responding to a speed reference signal generated at the computeroutput in digital form. Generally, the analog output block 362 comprisesan integrating amplifier to which up and down computer contact closureoutputs are coupled. Programmed computer operation determines the periodof closure of the respective contact outputs to determine the outputvoltage from the analog output block 362. In turn, the output voltagefrom the analog output block 362 is coupled to the computer 304 throughthe analog input system 308. The output contacts associated with theblock 362 are held open when the speed reference analog voltage isdetected to be at the digital command value.

With reference again to the error detector block 350, the summation ofthe speed reference, actual speed and speed feedback regulation signalsresults in the generation of a speed error output signal for applicationto a proportional plus rate amplifier 364. The amplified speed errorsignal is then inverted to obtain the correct polarity by an inverterblock 366. If no fuel demand limit action is applied, the speed errorsignal is further amplified by a mixer amplifier circuit block 368 togenerate a contact signal output (CSO) or a fuel demand signal on line369 for input to the fuel control system 337 and for fuel demand orcontrol output signal monitoring by meter 370.

A clamp circuit block 372 includes two circuits which are used to imposehigh and low limits on the fuel demand signal. A low limit setpoint of1.25 volts is generated by a low limit setpoint generator circuit block374 and applied to the negative input of clamp amplifier 376 forcomparison with the fuel demand signal which is applied to the positiveinput from the fuel demand amplifier 368.

Similarly, a high limit for the fuel demand signal is established by asetpoint signal generated by an analog output circuit block 378 and aninverter 380 and applied to the positive input of another clampamplifier for comparison with the fuel demand signal which is alsoapplied to the positive clamp amplifier input. The computer outputsignal coupled to the analog output block 378 is the lowest of the fueldemand limit representations generated by control blocks 318, 320, 322and 324 (FIG. 13A) under programmed computer operation.

The output of the clamp amplifier 382 is coupled to the input of theamplifier block 368 to produce low select fuel demand limit action onthe fuel demand signal. Similarly, the output of the clamp amplifier 376is applied to the input of the proportional plus rate amplifier 364through an analog switch 384 which becomes conductive if a low fuellimit signal LLCSOX has been generated by the computer, i.e. if the fueldemand signal has reached 1.25 V (logic shown in FIG. 33C), to preventflame out particularly on load transients through low limit fuel demandaction.

If the fuel demand signal tends to drop below 1.25 volts, the lowlimiter clamp amplifier 376 operates through the analog switch 384 toclamp the input to the proportional plus rate amplifier at a level whichresults in the fuel demand signal output from the circuit block 368having a voltage level of 1.25 volts. Similarly, the high limiter clampamplifier 382 clamps the fuel demand amplifier 368 to prevent the fueldemand signal from exceeding the present value of the fuel demand limitas determined and output by the computer 304.

The auxiliary or backup speed limiter 326 is preferably employed toprovide backup speed protection in conjunction with the main speedcontrol 324. The turbine speed value at which the backup speedprotection is provided is above the maximum speed range over which thespeed control 324 is intended to provide control. For example, themaximum speed reference value within the speed control range of thespeed control 324 may be 104% rated speed and the auxiliary speedlimiter circuit 326 may provide backup speed limit protection at a speedof 108% rated. The mechanical backup speed limiters associated with thefuel systems referred to previously in connection with FIGS. 9 and 10then provide further backup speed protection at a speed of 110% rated.

An auxiliary speed sensor 384 cooperates with the 44 tooth magneticwheel 345 on the turbine-generator rotating element to generate asinusoidal speed signal in the manner described for the main speedsensor 344. A pulse train is then generated by pulse train generatorblock 386 in the manner described for the circuit block 346 in the mainspeed control channel. Next, a converter block 388 generates an analogspeed signal in response to the pulse train output from the circuitblock 386 in the manner considered in connection with the main speedconverter circuit 348.

The backup speed limit is imposed on the turbine operation by an analogclamp circuit 390 in circuit block 391. The output of the amplifierclamp circuit 390 is applied to the summing junction input of the mixingamplifier 368 to produce limit action on the fuel demand signalgenerated by the amplifier 368 in a manner similar to that described inconnection with the limit action produced by the clamp amplifier circuit376.

More particularly, the backup speed clamp amplifier circuit 390 causesthe fuel demand signal to be cut back to the minimum value of 1.25 voltsto cause turbine deceleration without flameout when a speed limitersetpoint generator circuit 392 is caused to apply a low limit setpointof -1.25 volts to the positive input of the clamp amplifier forcomparison with the fuel demand signal which is also applied to thepositive input. An analog switch 394 is made conductive by input 395 tocouple a one volt supply to the input of the setpoint generator circuit392 and cause the generation of the low limit setpoint if either of twologic conditions is satisfied.

To provide low limit setpoint generation and auxiliary speed backupprotection if the turbine speed exceeds the predetermined limit value of108% as a first logic condition, the auxiliary speed signal is appliedto the input of a comparator circuit 396 which generates an outputsignal for application to an OR circuit 397 when the speed signal is toohigh. An AND circuit 400 responds if LLCSOX exists to generate aswitching signal at the input 395 of the analog switch 394 through alogic inverter 402.

The second logic condition which causes auxiliary speed backup limitprotection is preferably included so that the turbine operation is cutback if the rate of speed change is too great at any turbine speed valueover a predetermined speed range such as 102% rated speed to 108% ratedspeed. For this purpose, the auxiliary speed signal is applied to theinput of a rate amplifier 404 which generates a speed derivative signalapplied to the switching path of an analog solid state switch 406.

The speed derivative signal is coupled through the switch path of theswitch 406 to the input of another comparator 398 if the turbine speedis above the bottom range value of 102% rated speed. As indicated byreference character 407, a switching action input is applied to thespeed derivative analog switch 406 by a comparator 408 if the auxiliaryspeed signal applied to its input exceeds the predetermined valuecorresponding to 102% rated speed. If the turbine speed is excessive,the speed derivative signal is compared to a predetermined accelerationlimit by the comparator 398. If the acceleration is also excessive, anoutput from the comparator 398 is coupled through the logic circuits397, 400 and 402 to the control input of the logic switch 394 whichcauses low limit action on the fuel demand signal through the clampamplifier 390 as already described.

The fuel demand signal generated at the output of the fuel demandamplifier 368 accordingly is representative of the fuel needed tosatisfy the computer generated speed reference, the fuel needed tosatisfy a computer determined limit action, the low limit fuel demandneeded to prevent flameout during mormal speed operations, or to causeturbine speed cutback without flameout when overspeed conditions aredetected by the auxiliary speed limiter circuit 326. At an input 410 tothe dual fuel control system 337, the fuel demand signal is appliedacross a digital potentiometer 412 which is illustrated schematically asan analog potentiometer. The fuel demand signal is also applied to thecomputer analog input system 308 for programmed computer operations asindicated by the reference character 411.

In the leftmost position of the dual fuel demand potentiometer 412, thefuel demand signal is fully applied to a gas fuel control system 414. Inthe rightmost potentiometer position, the fuel demand signal is fullyapplied to a liquid fuel control system 416. At intermediatepotentiometer positions, the total fuel demand signal is ratioed betweenthe gas and fuel control systems 414 and 416 to produce the individualfuel flows which satisfy gas turbine operation commands.

The digital potentiometer position is determined by programmed computeroperation of contact output closures to produce the desired fuel ormixed fuel flow to the burners. Fuel transfer operations are also placedunder automatic computer control through the digital potentiometer 412,but that subject is considered more fully in the aforementionedcopending Reuther application.

The gas fuel demand signal is applied to the input of a signal rangeadjuster amplifier 418 to produce the predetermined gain and biascharacterization for operation of the gas start valve. Similarly, thegas demand signal is applied to the input of a signal range adjusteramplifier 420 to provide the predetermined gas throttle valvecharacterization. In FIG. 21, there are shown the respectivecharacterization 428 and 428 for the adjuster amplifiers 418 and 420.Further, there is shown a net starting valve and throttle valve gas flowcharacteristic 426 which results from the characterized control placedon the starting valve and throttle valve electropneumatic converters bythe amplifiers 418 and 420 as a function of the fuel demand controlsignal.

The gas fuel demand signal and the total fuel demand signal aredifferenced at the summing junction of an operational amplifier 422 togenerate the liquid fuel demand signal. As already indicated, the liquidfuel demand signal is equal to the total fuel demand signal when thepotentiometer 412 is positioned at its rightmost location to make thegas fuel demand signal zero.

A signal range adjuster amplifier 424 operates on the liquid fuel demandsignal to produce control on the liquid fuel throttle valveelectropneumatic converter in accordance with the characteristic 432shown in FIG. 22. The oil demand signal is also applied to the input ofan oil pressure reference generator 434 which generates a ramp referencefor a proportional plus reset plus rate controller 436. The pumpdischarge pressure transducer (FIG. 10) generates a feedback signalwhich is summed with the ramp reference and the resultant error signalis operated upon with proportional plus reset plus rate action by thecontroller 436 to operate the liquid fuel bypass valve electropneumaticconverter 270 in accordance with the pump discharge pressurecharacterization indicated by the reference character 438 in FIG. 22.When gas fuel is selected, the oil discharge pressure is regulated to apredetermined minimum value.

When the liquid fuel demand signal reaches a value of 1.25 volts, thepump discharge pressure ramp is terminated as indicated by the referencecharacter 440 in FIG. 22 and the pump discharge pressure is then heldconstant as indicated by the reference character 442 for higher liquidfuel demand signals. Thus, an analog clamp circuit 444 compares a limitvoltage generated by a limit setpoint generator 446 to the oil pressurereference signal and clamps the output from the oil pressure referencegenerator 434 at a value which causes the pump discharge pressure toremain constant at the value indicated by the reference character 442.

The inlet guide vane control 338 considered previously in connectionwith FIG. 12 includes a controller 448 which generates a guide vaneposition control signal as a linear function of the sensed speed signalderived from the error detector block 350 in the main speed channel. Aninlet vane electropneumatic converter 450 is provided for operating thepreviously mentioned positioning ring of the guide vane assembly. Asillustrated in FIG. 23, the controller position control signalcharacteristic 452 provides for a minimum open guide vane position atthe 20% ignition speed value and increased opening of the guide vaneswith increased turbine speed until the guide vanes are at the maximumopen position at approximately 95% rated turbine speed.

The synchronizer detection circuit 342 is responsive to sensed systemvoltage derived in this case from a bus potential transformer asindicated by the reference character 452 and sensed generator voltagederived in this instance from a generator potential transformer asindicated by the reference character 454 to detect the relativeconditions of the two sensed waveforms for operator or automaticsynchronization of the generator 102 with the system by closure of thegenerator breaker after completion of the startup period. For linebreaker synchronization, the inputs are computer switched to the properpotential transformers. Respective square wave signals are generated byZener diode clipped amplifiers 456 and 458 to which the system andgenerator voltage signals are respectively applied.

The two square waves are applied to an AND circuit block 460 whichgenerates an output only when both squarewave signals are in the ONcondition. In turn, an analog switch 460 applies an input to a phasedifference amplifier 464 during the time period that a signal isgenerated by the AND circuit block 460.

The output voltage from the phase difference amplifier is proportionalto the phase difference between the generator and system voltages and itis applied to an operator's panel voltmeter 466 for use by the plantoperator during manual synchronization. At the extreme limits, a 180°phase difference results in a phase difference voltage approaching zerovolts and a 0° phase difference results in a phase difference voltage of5 volts. The phase difference voltage is also applied to the computer304 through the analog input system 308 when programmed automaticsynchronization is employed.

It is also noteworthy that the generator voltage signal is phase shifted90° by a capacitor 468 for vector summation with the system voltagesignal at the input of a beat voltage generator amplifier 470. A diode472 operates in the amplifier circuit to cause a beat frequency signalto be generated for input to the computer 304 through the analog inputsystem 308 as a relative speed indication for programmed automaticsynchronizing.

Control Panels

The operator's panel 120 considered in connection with FIG. 1 isincluded as part of an operator's console and it is shown in greaterdetail in FIG. 24. Continuous display meters are provided for thefollowing turbine variables as indicated by the reference characters inparentheses:

Turbine Speed (Dual Scale)--(349)

Fuel Demand Signal--(502)

Vibration (Turbine or Generator)--(504)

Disc Cavity Temperature--(506)

Bearing Temperature (Turbine or Generator)--(508)

Exhaust Temperature--(510)

Blade Path Temperature--(512).

Continuous display meters are also provided for the following generatorvariables:

Watts (Dual Scale Optional)--(514)

VARS--(516)

Phase Difference for Synchronizing--(466)

Volts (Dual Scale Optional)--(518)

Amperes (Dual Scale Optional)--(520)

Stator Winding Temperature--(522)

Frequency--(524)

DC Field Amperes--(526)

DC Field Volts--(528)

Running Volts--(530)

Incoming Volts--(532).

Many of the meters or indicators can display one of several quantitiesas an operational and maintenance aid. The SELECT INDICATOR and SELECTDEVICE pushbuttons are used in conjunction with a two decade thumbwheelswitch 534 to select and display the desired quantities. Each selectivedisplay meter has an assigned number which can be set into thethumbwheel switch to cause that meter to be turned off when the SELECTINDICATOR pushbutton is pressed. If a variable such as a thermocoupletemperature is to be displayed, a number associated with the variable isregistered by the thumbwheel switch and the SELECT DEVICE pushbutton ispressed. The selected meter then indicates the selected variable.

During remote control, generator watts, VARS and phase A volts areautomatically selected for the remote watt, VAR and volt meterscorresponding to the watt, VAR and volt meters 514, 516 and 518. Thelocal operator panel pushbuttons effective during remote control are:

Turbine Emergency Stop

Local Control

Generally, a plurality of control pushbuttons are located in theillustrated arrangement beneath the meters just considered. One word ofcontact closure inputs and one interrupt is assigned to the operatorpanel 120. Identical additional assignments are made for each additionaloperator's panel used under multiple gas turbine plant control. Withinthe fourteen bit contact closure input word, eight bits are assigned forreading the two decade thumbwheel switch 534 and the other six bits areemployed to identify the pushbutton depressed to produce the computerinput.

All of the pushbuttons cause a circuit to be closed while depressed soas to cause a single normally open pushbutton contact to be connected toa diode matrix. A pushbutton operation energizes the common interruptthe operator's panel 120 and applies voltage to a unique combination ofthe six bits assigned to the pushbutton. The contact closure input wordis read within milliseconds and the bit combination is stored forfurther processing.

Operation of a second pushbutton while a first one is still depressedcauses no additional interrupt but generally only one pushbutton shouldbe operated at a time. Mechanical barriers are provided between adjacentpushbuttons, and critical group of pushbuttons are mechanicallyinterlocked.

Once a panel contact closure input word is read, it is repetitively readuntil the bit pattern changes to indicate that the pushbutton has beenreleased or another button has been depressed. In this manner, raise,lower and test actions can be continued during the period of pushbuttondepression.

The breaker pushbutton control switches are effective only under local,manual synchronizing control. In addition, lockout must be reset toclose the field breaker and the generator breaker must be tripped beforethe field breaker can be tripped. To close the generator breaker, thefield breaker must be closed, the master contact function must be in theON state, lockouts must be reset and the manual synchronizing equipmentmust be in service. The manual synchronizing equipment also must be inservice to close the line breaker.

Synchronizing ON and OFF pushbuttons are associated with both thegenerator and line breaker pushbuttons. If the synchronizing equipmentis in service for one breaker and a similar request is made for theother breaker, the request is ignored. The SYNC ON lamps are in parallelto display the fact that the synchronizing equipment is in useregardless of the row of breaker pushbuttons under observation.

A pair of synchronizing lights are placed under the speed meter 349 asshown to act as conventional synchronizing lights driven by reducedvoltage transformers in the transformers in the protective relaycabinet. The AUTO SYNC and MANUAL SYNC pushbuttons provide for selectingthe synchronizing mode to provide for generator breaker closing afterthe gas turbine 104 has been accelerated to idle speed.

With respect to gas turbine control, pushbuttons are provided for bothnormal and emergency starting and stopping. The emergency stop operationcauses immediate opening of the generator circuit breaker and turbineshutdown. The normal stop operation first reduces the load to minimum(approximately 10%) and turbine shutdown is then initiated.

The normal turbine start selection is combined with load selection.Thus, pressing the pushbuttons associated with minimum, base or peakload provides for initiating a normal turbine start. After the generatorbreaker is closed the selected load level is automatically generated.The minimum, base and peak load levels can be selected at any time, butthe system reserve load level can be selected by the associatedpushbutton only after the generator breaker has been closed. The SYSTEMRESERVE pushbutton accordingly cannot be used to initiate a start. Onemergency start, the gas turbine unit 104 is driven to the base loadlevel of operation after it has reached idle speed and the generatorbreaker has been closed. However, a different load can be selected ifdesired. The LOAD RAISE and LOAD LOWER pushbuttons provide manualcontrol over sped reference during synchronizing in Mode 2 and duringtemperature control in Mode 4. In Mode 3, these pushbuttons control thekilowatt reference.

The operator is provided with generator control by VOLT RAISE and VOLTLOWER pushbuttons which control generator voltage during manualsynchronization and after manual or automatic synchronization. A pair ofpushbuttons are also provided to control a pair of contact closureoutputs from the computer 304 to place the generator voltage regulatoron automatic or manual operation. On automatic operation, the voltageregulator is switched into service when the generator field breakercloses. The VOLT RAISE and VOLT LOWER pushbuttons control the baseadjusting rheostat in manual operation and the voltage adjustingrheostat in automatic operation.

Pushbuttons are also provided for fuel selection, in this instance gasor oil or an oil and gas mix. Another pushbutton provides for automatictransfer between gas and oil prior to burner ignition or aftersynchronization or from gas to oil on loss of gas supply pressure. Thegas turbine unit 104 can be started on gas or oil, and if a fuel mix isselected, the gas turbine 104 starts on gas and mixes oil to apredetermined ratio after synchronization. The predetermined gas/oilratio in the fuel mix can be varied with the use of the thumbwheelswitch 634 and the SELECT DEVICE and SELECT INDICATOR pushbuttons.

On the occurrence of an alarm, the light is flashed and a horn blow iscaused unless the plant is under remote control. A HORN SILENCEpushbutton provides for stopping the horn blow. The ALARM RESETpushbutton causes any flashed alarm to go from the flashing condition toa steady ON condition and the turbine lockout conditions to be reset.When the faulty conditions are cleared, the alarm lamp goes dark.Generator lockout relays are flashed when tripped by the GEN TRIP ALARMlight and they must be reset manually. A LAMP TEST pushbutton causes alllights on the operator's panel 120 to flash ON and OFF for lamp testpurposes.

The following startup sequence lamps are located in a bottom row acrossthe bottom of the operator's panel 120:

    ______________________________________                                        Color          Function                                                       ______________________________________                                        Red            Turbine Auxiliaries Reset                                      Red            Turbine Trip Reset                                             Green          Ready to Start                                                 Red            Master Control On                                              Yellow         Auxiliary Pump On                                              Red            Turbine Tube Pressure 63-4                                     Yellow         Turning Gear On                                                Red            Lube Pressure 63-1                                             Yellow         Start Device On                                                Red            Overspeed Trip Valve                                           Yellow         Overspeed Trip Pressure                                        White          Ignition On                                                    Red            Fuel On                                                        Red            Flame Combustor 6                                              Red            Flame Combustor 7                                              White          Start Device Off                                               White          Auxiliary Pump Off                                             Red            Field Breaker 41                                               Red            Bleed Valve Closed                                             Yellow         Synchronous Speed                                              Red            Generator Breaker 52G                                          ______________________________________                                    

Some of the startup sequence lights are pushbuttons which can bedepressed before or during a startup to cause the startup sequence tohold at the process point represented by the pushbutton. A HOLDpushbutton causes the speed reference to stop advancing duringacceleration, and it is automatically cleared on shutdown. The holdpoint pushbuttons flash when selected and, at the selected hold point,the corresponding light burns steady and the HOLD pushbutton lightflashes. A hold is released by depressing the GO pushbutton which has alight normally not lit but energized during lamp test for uniformity.The HOLD POINT pushbuttons are AUX PUMP ON, TURNING GEAR ON, STARTDEVICE ON, OS TRIP PRESS, and SYNC SPEED. Maintenance operations arefacilitated with the use of the sequence lights and pushbuttons and theHOLD and GO pushbuttons. The operator's panel 120 also provides forselection of local control or remote control by the associatedpushbutton. A DEMAND REVIEW pushbutton provides for printout of currentalarm conditions.

One operating advantage associated with the operator's panel 120 and itsinteraction with other elements of the control system 300 is thatselected analog and CCl points can be read and selected CCO points canbe operated in conjunction with plant maintenance operations. Amongother advantages, control system potentiometers and other adjustableelements can be conveniently manipulated for meter calibrations duringsetup procedures.

An annunciator panel to which reference was previously made inconnection with FIG. 19B can be mounted on top of the operator's panel120 on the control console. The annunciator panel can be part of analarm system and it contains a predetermined number of lamps driven byrespective contact closure outputs from the computer 304.

The vibration monitors to which reference has already been made are alsomounted in the operator's control console. Similarly, flame detectionmonitors are mounted at the control console.

A remote control panel 536 is shown in greater detail in FIG. 25. Itincludes meters 538, 540 and 542 which display the indicated quantitiesor quantities selected at the local operator's panel in the mannerpreviously indicated. The remote panel control pushbuttons duplicate thefunctions of the corresponding pushbuttons on the local operator's panel120.

When a remote control pushbutton is depressed, a diode matrix convertsthe operation to an interrupt and a five bit binary code. The remoteinterrupt channel is provided in addition to the local operator's panelinterrupt channel, and five separate contact closure inputs are providedfor the remote panel 536. The lamps provided for the control pushbuttonsincluded with the remote panel 536 are connected in parallel withcorresponding lamps on the operator's panel 120. Generally, the remotepanel 536 is suitable for direct wire connection up to 2500 feet fromthe operator's panel 120.

If supervisory control is selected, the remote control panel 536 is notused. Instead, the local supervisory contacts are coupled to thecomputer system 305 where a diode matrix converts them to an interruptand a five bit code for connection to the five contact closure inputsotherwise used for remote panel operation. Seven contact closure outputsare employed to indicate the status of the local operator panel lampsotherwise connected to the remote panel.

The following listings respectively describe the local and remoteoperator's panel pushbutton codes, the operator's panel contact closureoutput assignments, and the entering of control parameter changes intothe control system 300.

    ______________________________________                                        LOCAL OPERATOR'S PANEL PUSHBUTTON CODES                                       Octal   Matrix   Switch    Pushbutton                                         Code    Terminal Iden.     Description                                        ______________________________________                                        00      --       --          --                                               01      1-1      S-100     Fld. Bkr. Trip                                     02      1-2      S-101     Fld. Bkr. Close                                    03      1-3      S-103     Gen. Bkr. Trip                                     04      1-4      S-104     Gen. Bkr. Close                                    05      1-5      S-106     Load Raise                                         06      1-6      S-107     Load Lower                                         07      1-7      S-110     Min. Load Norm. Start                              10      1-8      S-111     Base Load Norm. Start                              11      1-9      S-112     Peak Load Norm. Start                              12      1-10     S-102     Sync. Off (Gen)                                    13      1-11     S-105     Sync. On (Gen.)                                    14      1-12     S-116     Reg. Man.                                          15      1-13     S-117     Reg. Auto.                                         16      1-14     S-113     System Reserve                                     17      1-15     S-114     Volts Raise                                        20      1-16     S-115     Volts Lower                                        21      1-17     S-130     Select Indicator                                   22      1-18     S-131     Hold                                               23      1-19     S-120     Sync. Off (Line)                                   24      1-20     S-123     Sync. On (Line)                                    25      1-21     S-121     Line Bkr. Trip                                     26      1-22     S-122     Line Bkr. Close                                    27      1-23     S-165     Turning Gear (Hold 2)                              30      1-24     S-163     Aux. Pump on (Hold 1)                              31      1-25     S-167     Start Device on (Hold 3)                           32      1-26     S-171     O.S. Trip Pres. (Hold 4)                           33      1-27     S-154     Local Control                                      34      1-28     S-155     Remote Control                                     35      1-29     S-133     Go                                                 36      1-30     S-202     Sync. Speed (Hold 5)                               37      --       --          --                                               40      --       --          --                                               41      2-1      S-124     Auto. Sync.                                        42      2-2      S-125     Man. Sync.                                         43      2-3      S-134     Turbine Emerg. Stop                                44      2-4      S-135     Turbine Normal Stop                                45      2-5      S-136     Spare                                              46      2-6                Spare                                              47      2-7      S-132     Select Device                                      50      2-8      S-150     Gas Fuel Only                                      51      2-9      S-151     Oil Fuel Only                                      52      2-10     S-153     Oil and Gas Mix                                    53      2-11     S-152     Gas Pressure Low Pres.                                                        Transfer                                           54      2-12     S-140     Turbine Emerg. Start                               55      2-13     S-157     Demand Review                                      56      2-14     S-145     Horn Silence                                       57      2-15     S-146     Alarm Reset                                        60      2-16     S-147     Lamp Test                                          61      2-17                                                                  62      2-18     --                                                           63      2-19     --                                                           64      2-20     --                                                           65      2-21     --                                                           66      2-22     --                                                           67      2-23     --                                                           70      2-24     --                                                           71      2-25     --                                                           72      2-26     --                                                           73      2-27     --                                                           74      2-28     --                                                           75      2-29     --                                                           76      2-30     --                                                           77      --       --                                                            Prototype - channel 20.sub.8 bits 5-0 Interrupt Location 22.sub.8             ##STR1##                                                                     ______________________________________                                         REMOTE OPERATOR'S PANEL PUSHBUTTON CODES                                                     Switch                                                        Octal  Matrix   Identi-  Pushbutton                                           Code   Terminal fication Description                                          ______________________________________                                        00     --       --                                                            01     1        S-1      Minimum Load Normal Start                            02     2        S-2      Base Load Normal Start                               03     3        --         --                                                 04     4        S-4      System Reserve                                       05     5        --         --                                                 06     6        --         --                                                 07     7        S-5      Spare                                                10     8        S-6      Load Raise                                           11     9        --         --                                                 12     10       --         --                                                 13     11       S-15     Volt Raise                                           14     12       --         --                                                 15     13       S-17     Lamp Test                                            16     14       --         --                                                 17     15       --         --                                                 20     16       --         --                                                 21     17       S-18     Gas Fuel Only                                        22     18       S-19     Oil Fuel Only                                        23     19       S-3      Peak Load Normal Start                               24     20       S-20     Gas Fuel Low Pressure Transfer                       25     21       S-13     Turbine Normal Stop                                  26     22       S-14     Turbine Emergency Start                              27     23       S-21     Oil and Gas Mix                                      30     24       S-22     Generator Breaker 52G                                31     25       S-7      Load Lower                                           32     26       S-8      Spare                                                33     27       S-23     Regulator Manual                                     34     28       S-16     Volt Lower                                           35     29       S-24     Regulator Auto                                       36     30       S-25     VM                                                   37     --       --                                                            ______________________________________                                        OPERATOR'S PANEL CCO ASSIGNMENT                                               Prototype                                                                             Lamp             Description of                                       Word  Bit   Iden.**          Indication                                       ______________________________________                                        01    00    (S-100), S-101, S-200                                                                          Fld. Bkr. Position                               ↓                                                                            01    (S-103), S-104, S-203                                                                          Gen. Bkr. Position                               ↓                                                                            02    S-106, S-107, S-114, S-130,                                                                      --                                             ↓    S-132, S-145, S-146, S-147                                        ↓                                                                            03    *--              KWH Counter Contact                              ↓                                                                            04    S-110            Min. Load                                        ↓                                                                            05    S-111            Base Load                                        ↓                                                                            06    S-112            Peak Load                                        ↓                                                                            07    (S-102), S-105   Sync. Sw. - Gen.                                 ↓                                                                            08    (S-116), S-117   Reg. Auto. (Man.)                                ↓                                                                            09    S-113            System Reserve                                   ↓                                                                            10      --               --                                             ↓                                                                            11      --               --                                             ↓                                                                            12      --               --                                             ↓                                                                            13    S-131            Hold                                             02    00    (S-120), S-123   Sync. Sw. - Line                                 ↓                                                                            01    (S-121), S-122   Line Bkr. Position                               ↓                                                                            02    S-160            Turbine Aux. Reset                               ↓                                                                            03    S-161            Turbine Trips Reset                              ↓                                                                            04    S-162            Master Control On                                ↓                                                                            05    S-164            TG Lube Pres. 63-4                               ↓                                                                            06    S-165            Turning Gear                                     ↓                                                                            07    (S-163), S-177   Aux. Pump Off                                    ↓                                                                            08    (S-167), S-176   Start Device Off                                 ↓                                                                            09    S-166            Lube Pres. 63-1                                  ↓                                                                            10    S-170            O.S. Trip Valve                                  ↓                                                                            11    S-171            O.S. Trip. Pres.                                 ↓                                                                            12    S-172            Ignition On                                      ↓                                                                            13    S-173            Fuel On                                          03    00    (S-154), S-155   Remote Control (Local)                           ↓                                                                            01    ( -- ), S-133    Go                                               ↓                                                                            02    S-174            Flame Comb. 6                                    ↓                                                                            03    S-175            Flame Comb. 7                                    ↓                                                                            04    S-201            Bleed Valve Closed                               ↓                                                                            05    S-207            Ready to Start                                   ↓                                                                            06    S-202            Syn. Speed                                       ↓                                                                            07    (S-124), S-125   Man. Sync. (Auto)                                ↓                                                                            08    ( -- ), S-142    Alarm                                            ↓                                                                            09    S-143            Gen. Trip                                        ↓                                                                            10    S-134            Turbine Emerg. Stop                              ↓                                                                            11    S-135            Turbine Normal Stop                              ↓                                                                            12    S-136            Spare                                            ↓                                                                            13    S-156            Gas Xfer. Press. Normal                          04    00    *(S-150), S-151  (Gas Fuel Only),                                 ↓                     Oil Fuel Only                                    ↓                                                                            01    *(WD03, Bit 00), S-153                                                                         Oil Gas Mix                                      ↓                                                                            02    S-152            Gas Pres. Low Pres.                              ↓                     Transfer                                         ↓                                                                            03    *--              Horn Contact                                     ↓                                                                            04    S-140            Turb. Emerg. Start                               ↓                                                                            05    S-157            Demand Review                                    ↓                                                                            06    S-144            Turbine Shutdown                                 ______________________________________                                         *NOTE:                                                                        Refer to Schemes Below:                                                       ##STR2##                                                                      **NOTE:                                                                       Parentheses indicate N.C. contact                                        

CONTROL PARAMETER CHANGES 1. General

Any core location in the P-50 computer can be changed through the ASR-35typewriter. This set of instructions is an aid in selecting the propercore location and value. All locations appear in the listings for thecontrol and sequence programs and their resident tables.

The general procedure, after having determined the proper location(s)and value(s) is as follows:

a. Preferably make changes with the turbine(s) shutdown and the "SYNC"switch on the P-50 maintenance panel turned off. If not, typing speedmust be slowed so that the keys are only struck when the acknowledgelamp in the yellow attention interrupt button on the ASR set is lit.Typing too fast with "SYNC" on may result in error messages ormisreading of the information.

b. Octal dump the locations to be changed and check their contentsagainst the listings if possible to verify that the correct location hasbeen chosen--also to know what was in core in case it must be restored.

c. Set the limits for loading as close as possible (1 location if only 1is to be changed) to limit the effect of errors.

d. Numeric load the information taking care if "SYNC" is on, to onlytype when the yellow light on the ASR set is on.

e. Octal dump the locations to verify that the correct information hasbeen entered. Note if decimal information had been loaded by precedingthe value with a + or (-) sign, the octal equivalent will print out.

f. Binary punch the locations changed if the change is to be permanentand attach tape to the end of the proper computer punched paper tape.

2. Bearing, Disc Cavities, Vibration

Alarm and shutdown values are stored as octal ADC values for disc cavitytemperatures and vibration values. To convert 1000° F. to ADC type:

    EA +1000/1

To convert 4 mils to ADC for vibration, type:

    EA +400/161

(The symbol represents a space and line feed and return. Typing ispreceeded by attention interrupt. The ASR set will type back the ADCvalue, the index and the value with the correct decimal place.

The locations when these are stored are listed below. Note bearings,etc, having the same alarm or shutdown level may use a common locationand changing the level for 1 may change the level for a group.

    ______________________________________                                                                           Shutdown                                   Mnemonic                                                                              Description    Alarm Location                                                                            Location                                   ______________________________________                                        DC1     Disc Cavity 1  15311       15315                                      DC2     Disc Cavity 2  15312       15316                                      DC3     Disc Cavity 3  15313       15317                                      DC4     Disc Cavity 4  15314       15320                                      LT17    Gen. Brg. Drain                                                               (Gen. End)     *           15507                                      LT18    Gen. Brg. Drain                                                               (Turb End)     *           15510                                      LT19    Pinion Brg. Drain                                                             (Gen. End)     *           15511                                      LT20    Main Gear Drain                                                                              *           15512                                      LT21    Pinion Brg. Drain                                                                            *           15513                                      LT22    Comp. Journal Brg.                                                            (Babbitt)      *           15514                                      LT23    Thrust Bearing Shoe                                                           (Babbitt)      *           15515                                      LT235   Thrust Bearing Shoe                                                           (Babbitt) Spare                                                                              *           15516                                      LT24    Turb. Brg. (Babbitt)                                                                         *           15517                                      LT25    Gen. Brg. Drain                                                               (Turb. End)                                                                   (In Board)     *           15520                                      LT26    Gen. Brg. Drain                                                               (Exc. End)     *           15521                                      LT36=                                                                         LT33    Gear Support Metal                                                            Temp. Diff.    Shutdown only                                                                             17275                                      39V1    Exc. Vib.-Starting                                                                           14307       14270                                      39V2    Gen Vib.-Exec. End-                                                           Starting       14307       14270                                      39V3    Gen Vib.-Comp. End-                                                           Starting       14307       14771                                      39V4    Comp. Vib.-Starting                                                                          14307       14771                                      39V1    Exec. Vib.-Running                                                                           14304       14271                                      39V2    Gen. Vib.-Exec. End-                                                          Running        14304       14271                                      39V3    Gen. Vib.-Comp. End-                                                          Running        14304       14775                                      39V4    Comp. Vib.-Running                                                                           14304       14775                                      ______________________________________                                         * Alarms . . . a nominal 6° Delta before shutdown. This delta valu     is stored in location 17647.                                             

3. Generator Resistance Temperature Detectors

All 6 generator RTD readings may be displayed on the operator's consolebut only 1, RTD1, is checked for exceeding the alarm temperature limit.After operating experience has been gained the hottest RTD should beconnected to the #1 RTD bridge. This is the one connected to terminalsJ15 and J16 on half shell 0051 for turbine A and half shell 0111 forturbine B.

    ______________________________________                                        Mnemonic    Description    Alarm Location                                     ______________________________________                                        RTD1        Generator RTD 1                                                                              17635                                              ______________________________________                                    

The octal ADC value for a temperature level in ° F. may be found bytyping (for 221° F. or 105° C.):

    EA +2210/63

4. Deadbands

Several functions use deadbands for operation or alarm and shutdown. Toconvert engineering units to the proper ADC units use the ASR set as inthe following samples and enter the octal ADC values as desired in thelocations listed below.

    ______________________________________                                        1. Percent Speed (70%) EA +700/273                                            2. Combustor Shell Pressure (68 PSIG)                                                                EA +680/327                                            3. Thermocouple Temperature (180° F.)                                                         EA +180/1                                              Input to                   High     Low                                       Deadband Function          Location Location                                  ______________________________________                                        LT29     Low oil cooler fan                                                                              13734    13732                                     LT29     High oil cooler fan                                                                             13731    13727                                     LT33     High oil cooler fan                                                                             13726    13723                                     LT29     Turning gear permissive                                                                         13366    13363                                     14M      Starting device permissive                                                                      13356    13354                                     COMBR    Bleed Valve 1 operation                                                                         13711    13706                                     COMBR    Bleed Valve 2 operation                                                                         13711    13706                                     LT29     52G Close permissive                                                                            14347    14344                                     LT29     Alarm and shutdown                                                                              17310    17305                                     LT28     Start permissive  14730    14725                                     LT35     Fuel Pump Inlet   17272    17267                                     ______________________________________                                    

5. Second Time Delays

Each second timer has 2 locations it uses. Both should be set to the newnumber, preferably when the turbine is not being fired. The decimalnumber to be numeric loaded is 5/6 of the number of seconds time delaydesired rounded to the nearest integer. Thus to get a 300 second timedelay, the number to be entered is 5/6×300 or +250. Note that the + signmust be used for the number to be interpreted as a decimal number.Limits for loading must be set first and a typical entry using the ASRset is shown here:

    ______________________________________                                                  LM 10025/10026                                                                NL                                                                            = 10025                                                                       + 250                                                                         + 250                                                               ______________________________________                                    

Note the closed parenthesis is the termination character for a numericload. The timers are listed in the sequence program resident tables butare repeated below for convenience. Note that when the values are octaldumped, the octal equivalent of the decimal will be typed. Maximum delayis 9828 seconds. Independent locations are furnished for each turbine.

    ______________________________________                                                                 Turb. A   Turb. B                                    Timer  Description       Locations Locations                                  ______________________________________                                        STD0   Seq. check 1 (ignition)                                                                         10015-16  10145-46                                   STD1   Ignition          10017-20  10147-50                                   STD2   Purge             10021-22  10151-53                                   STD3   Seq check3(Flame verifi-                                                      cation)           10023-24  10153-54                                   STD4   Seq. check 4(Motor                                                            Trip to idle)     10025-26  10155-56                                   STD5   Turning Gear      10027-30  10157-60                                   STD6   Vibration shutdown                                                                              10031-32  10161-62                                   STD7   Spare             10033-34  10163-64                                   STD8   Seq check 2 (O.S.T.Press)                                                                       10035-36  10165-66                                   STD9   OPX               10037-40  10167-70                                   STD10  Atomizing air     10041-42  10171-72                                   STD11  639 DS            10043-44  10173-74                                   STD12  L636 Prestart     10045-46  10175-76                                   STD13  Volt. adj. rheostat                                                           prestart          10047-50  10177-200                                  STD14  AC & DC Transfer Pump                                                         Motor Control     10051-52  10201-02                                   STD15  AC & DC Transfer Pump                                                         Motor Control     10053-54  10203-04                                   STD16  AC & DC Transfer Pump                                                         Motor Control     10055-56  10205-06                                   STD17  Fuel Oil under pressure                                                                         10106-07  10236-37                                   ______________________________________                                    

6. Hour Time Delays

The hour time delays are set similar to the second time delays but have3 locations associated with each. The first location should beinitialized to +3000 while the other 2 should be loaded with the time inhours minus 1 as a decimal number. Maximum delay is 8192 hours. Beloware the locations:

    ______________________________________                                        Timer Description Turbine A Locations                                                                         Turb. B Locations                             ______________________________________                                        HTD0  Auto Start  10004-06      10134-36                                      HTD1  Cooling period                                                                            10007-11      10137-41                                      HTD2  Shutdown    10012-14      10142-44                                      ______________________________________                                    

7. Curves

Individual curves for each trubine appear in the control resident table.Each curve is stored as 5 sets of coordinates. The 5 values of theindependent variable are stored first and must be in ascending order.Next come the 5 associated values of the dependent variable. Thus thecurves are approximated by 4 straight lines defined by 5 points. Thelines are extrapolated beyond the end points of the curve. However, thecontrol signal output, CSO is limited to 0-5 V, and this feature may beused to gain another line segment at 0 CSO in the surge curve at lightoff.

Except for the acceleration curves, the parameters are stored as octalADC/2. Sample "EA" conversions from engineering units to ADC/2 are shownhere:

    ______________________________________                                        1. Pressure (112PSG)                                                                            EA + 1120/327/2                                             2. Temperature (1000° F.)                                                                EA + 1000/1/2                                               3. CSO (1 Volt)   EA + 100/323/2                                              ______________________________________                                    

In the case of the acceleration curves, speed is the independentvariable and acceleration is the dependent variable. At intermediatespeed points the acceleration is interpolated giving a smoother curveand allowing easier matching at ignition and transfer from normal toemergency acceleration and back during acceleration. The decimal valuestored for speed is the speed in RPM while the decimal value stored foracceleration is 38.4 times the acceleration in RPM/sec.

As an aid in selecting values of speed for which the acceleration is tobe stored it is suggested that ignition speed and synchronous speed beselected. At ignition speed, the acceleration must be somewhat greaterthan that expected at ignition with minimum pump pressure or speedcontrol may tend to reduce the pump pressure until a flameout occurs.Another desirable point is at a point of inflection where accelerationstops decreasing and begins increasing. If there is a long linear regionwith constant acceleration, it is probably best to choose a point ateach end of the linear region.

A cut and try method may be used where tangents are drawn to theacceleration curve (speed (w) vs. time (t)) at the selected speedpoints. With the turbine at rest or on turning gear, the curve can bechecked by changing the control program to jump to mode 1 instead ofmode 0 and recording the speed reference (test point 11) on a stripchart recorder. Restoring the control program will bring the speedreference back down to track 11/2% above the turbine speed. Theacceleration values may be modified and the resulting curve checked onthe recorder until the desired starting curve is attained.

Another method is offered which predicts the necessary accelerationvalues more accurately. If the acceleration (α₁) is known at one end ofa curve segment, the necessary acceleration (α₂) at the other end of thesegment may be calculated knowing the desired change in speed (Δω) forthe desired time increment (Δt). This calculated value may then be usedto determine the acceleration needed at the other end of the next curvesegment, etc. until all acceleration coordinates have been determined.Since acceleration at ignition is critical, it is best to start at thisend of the curve.

In FIG. 1, the slope or acceleration at point 1 is α₁, expressed asRPM/sec, and at point 2 it is α₂. The following relationship applies:##EQU2##

The accompanying curve (FIG. 1) may be used to determine the ratio α₂/α₁ knowning α₁ Δt/Δω. Knowing α₁ and α₂ /α₁₃ α₂ may be easily found.This α₂ becomes α₁ for the next segment etc. until all 5 accelerationvalues are determined for storage. The curve should be checked on astrip chart recorder as described previously. Note the speed ref.amplifier is limited to about 36 rpm/sec.

The surge function is really a 2 input parameter function. Two curvesare stored, 1 for a low compressor inlet temperature (-40° F.) and 1 fora high temperature (+120° F.). The ADC/2 values for these 2 temperaturesare stored at the 1st 2 locations followed by 2 sets of curvecoordinates corresponding to these 2 temperatures. Each curve isevaluated for the given combustor shell pressure and then the finalvalue is determined by interpolating between these two points as afunction of compressor inlet temperature.

The following table is given to assist in locating the curve in thecontrol resident tables.

    __________________________________________________________________________            TURBINE A                                                                              TURBINE B                                                    MNEMONIC                                                                              1st LOCATION                                                                           1st LOCATION                                                                           DESCRIPTION                                         __________________________________________________________________________    EMGACC  33426    33676    Emergency Acceleration (option)                     NRMACC  33307    33357    Normal Acceleration                                 NORMST  33323    33573    Normal Start Temperature                            BASELD  33335    33605    Base Load Temperature                               PEAKLD  33347    33617    Peak Load Temperature                               SYSRLD  33361    33631    System Reserve Load Temperature                     SURGFN  33373    33643    Surge Curves                                        Miscellaneous Control Locations                                                       TURBINE A                                                                              TURBINE B                                                    MNEMONIC                                                                              LOCATION LOCATION DESCRIPTION        UNITS                            __________________________________________________________________________    SPLMIT  33267    33537    Max. speed after acceleration + RPM                 PATTERN 33247    33517    Loading Rate Pattern                                DIFERR  33272    33542    Differential Temp. Error                                                                         ADC/2                                                      Limit                                               MAX BPT 33273    33543    Maximum Blade Path Temp.                                                                         ADC/4                            MAX EXT 33274    33544    Maximum Exhaust Path Temp.                                                                       ADC/4                            Auto Synch.                                                                             LOCATION         DESCRIPTION                                        __________________________________________________________________________              6723             Gen Bkr Closing Time                                          --              Line Bkr Closing Time                              __________________________________________________________________________

D. PROGRAM SYSTEM 1. General Configuration

The computer program system is organized to operate the computer system305 so that it interacts with other control system elements and plantdevices to operate the gas turbine plant 100 and other similar plants asrequired to produce electric power with many user advantages. Asschematically illustrated in FIG. 26, the program system comprises asequencing program 600 and a control program 602 which make most of theplant operational determinations for output to the control systeminterfacing and control hardware. An executive program 604 schedules theuse of the computer 304 by the various programs in the software systemin accordance with a predetermined priority structure. The executiveprogram 604 also provides certain other functions considered more fullysubsequently.

Generally, the sequencing program 600 accepts contact closure inputs,analog inputs, and operator console inputs from an operator consoleprogram 606 to provide through contact closure outputs plant startup andother functions including alarm and houskeeping tasks prior to, duringand after startup. As indicated in FIG. 26, the sequencing program 600supervises the control program 602 by specifying the control mode andthe selected load. The control program 602 transmits data to thesequencing load. The control program 602 transmits data to thesequencing program 600 including for example hot blade path temperatureindications during load operation which require plant alarm andshutdown.

An automatic synchronization program 608 is also supervised by thesequencing program 600 to provide for generator voltage regulatorrheostat operation and turbine speed adjustment during automaticsynchronization. The sequencing program 600 processes manualsynchronization operation. It also transmits lamp light determinationsto the operator's console program 606 and alarm determinations to analarm program 610.

The operator's console program 606 is a package of subprograms whichprovides for interfacing the operator's panel 120 with the computer 304.The alarm program 610 provides for printout of detected alarms.

During the various modes of plant operation, the control program 602makes intermediate control determinations which result in thedetermination of a turbine speed reference representation and a fueldemand limit representation for application as analog signals to theanalog speed control 324 as previously described. Analog outputs fromthe control program 602, the automatic synchronization program 608 andthe operator's console program 606 are processed by an analog outputpulser program 612 to provide for generation of accurate external analogvoltages corresponding to the internal digital determinations. Analoginputs for the sequencing program 600 and the control program 602 andother programs are determined and stored by an analog scan executiveprogram 614.

A thermocouple check program 616 makes a validity check on thethermocouples not checked by the sequency program 600 or the controlprogram 602 and generates an alarm for alarm program printout when athermocouple reading indicates an open circuit. A log program 618operates in conjunction with a conversion program 620 to generate aperiodic printout of the values of predetermined analog inputs. Otherprograms included in the program system are classified as miscellaneousprograms 622.

2. Executive Systems

Generally, the executive program 604 provides for the execution of otherprograms on a priority basis, facilitates communication between theinput and output equipment and other programs in the program system, andstandardizes the handling of interrupts from the interrupt system 314.In the particular case of the P50 computer system, the executive programis a commercially available package which is operable in a wide range ofapplications. For a particular application like that present one, theexecutive program is initialized or tailored to the particularapplication by the entry of certain system parameters. Since theexecutive program is per se a part of the prior art, its functioningwill be considered here only insofar as it will aid in reaching anunderstanding of the program system and the control system and powerplant operations of the preferred embodiment.

In the program system, the individual programs are repeatedly executed,typically with only the program variables changed. The executivepriority system accordingly defines the order in which programs areexecuted since some programs must be executed as soon as data isavailable while other programs are of lesser importance. In the P50executive priority structure, a dominant priority level and a secondarypriority level are provided. Each of the main priority levels in turn isdivided into a number of sublevels. Generally, higher numbers implyhigher sublevel priority.

The priority executive program administers the priority scheme outsidethe priority structure. On the dominant level, programs are executedaccording to real time, i.e. a program which is first bid is executedfirst if two programs are bidding to run simultaneously. On thesecondary level, the programs are executed according to a preestablishedorder. Any time two programs are bidding to run the program on thehighest sublevel is executed first. On both main priority levels, theprograms run to completion before another program can be started on thatlevel.

Dominant level programs can be initiated periodically through anauxiliary synchronizer routine, or they may be initiated by interrupt,or they may be initiated by an error condition detected by a programexecution on a sublevel of the secondary level. The secondary lowerpriority level runs when the dominant level is not running. Thesecondary level in this case contains 14 sublevels which run accordingto a calling priority established when the executive program 604 isinitialized. A sublevel program may be bitting to run, running, in timedelay, suspended, or turned off. Once a sublevel is initiated, it cannotbe interrupted by a sublevel with higher priority on the secondarylevel. When a sublevel program turns off, is suspended or enters a timedelay, the sublevel program with the highest calling priority which isbidding will run. Generally, the majority of the programs in the gasturbine power plant program system are assigned to the secondary level.

The priority executive element of the executive program 604 comprisesthe following executive programs:

1. Bid Executive for the Dominant Level--This program permits a programor an interrupt routine to place a dominant sublevel into the biddingstate; a program on the dominant level cannot bid for another program onthe dominant level.

2. Bid Executive for the Secondary Level--This program permits a programor an interrupt routine to place a secondary sublevel into the biddingstate.

3. Turn Off Program Executive for the Dominant Level.

4. Turn Off Program Executive for the Secondary Level.

5. Time Delay Executive for the Secondary Level--This program routine isavailable only on the secondary level and it provides for downcounting atime delay with the synchronizer interrupt routine.

6. Suspend Program Executive for the Secondary Level--This program isalso only available on the secondary level and it permits a call for anindefinite time delay.

7. Unsuspend Program Executive for the Secondary Level--This program isused in conjunction with the suspend program executive.

The following table provides a definition of the priority levelsemployed in the program system used to operate the P50 computer system305:

    ______________________________________                                         PRIORITY LEVELS                                                              ______________________________________                                        Dominant Level Programs                                                       1.        Analog output pulsing, span adjust and scan.                        2.        Operator's Console A.                                               3.        Operator's Console B.                                               4.        Operator's Console C.                                               5.        Operator's Console D.                                               6.        Automatic Synchronizing A                                           7.        Automatic Synchronizing B.                                          8.        Automatic Synchronizing C.                                          9.        Automatic Synchronizing D.                                          10.       Spare                                                               11.       Spare                                                               12.       Spare                                                               13.       Spare                                                               14.       Spare                                                               ______________________________________                                        Secondary Sublevel Programs                                                   Sublevel  Description                                                         ______________________________________                                        14        Spare                                                               13        Message Writer Device 0                                             12        Operator's Console                                                  11        Sequencer                                                           10        Control                                                             9         Dead Computer                                                       8         Analog Output                                                       7         Alarm                                                               6         Spare                                                               5         Logging                                                             4         Horn and Alarm Lamp                                                 3         Cold Junction Comp.                                                 2         Thermocouple Check                                                  1         Programmer's Console                                                0         Confidence Check Conex                                              ______________________________________                                    

The executive program 640 also includes an input/output program which isavailable to control the communication of digital variables between thecomputer 304 and the input/output systems. In this case, only the outputcontacts are grouped into registers to be placed under executive programcontrol. Requests for contact outputs are queued by the input/outputexecutive program and control is returned to the calling program until ahardware interrupt indicates the external circuitry is ready to accept acontact output. Input contacts are random accessed in the present case.The input/output executive element of the executive program 604 furtherincludes the following subelements:

Bidding Subroutine

Input/Output BCD Character Routines

Contact Closure Output Executive

Programmer's Console Executive

Message Writer Executive.

Generally, an interrupt is initiated by a piece of hardware external tothe computer 304. An interrupt stops the current program executionunless it is locked out or temporarily inhibited. The interruptioncauses a branch to an interrupt routine which is identified by theinterrupt and the program structure. Generally, all interrupt routinesprovide for saving and restoring registers so that the interruptedprogram can again be processed from the interrupt point. Lockout can begenerated by hardware or software.

Executive interrupts initiate programs which are executed under hardwareinterrupt lockout. Process interrupts initiate programs which areexecuted under software lockout on the dominant level.

The following executive interrupt routines are included in the executiveprogram 604:

Synchronizer Interrupt

Contact Closure Output Completion Interrupt

Programmer's Console Attention Interrupt

Programmer's Console Input Interrupt

Programmer's Console Output Interrupt

Device Output Completion Interrupt

The executive program 604 also includes a multiply/divide program. Themultiply routine develops a 28 bit product from two 14-bit factors andthe divide routine produces a 14 bit quotient from a 28 bit dividend anda 14 bit divisor. A binary to BCD conversion program is also included inthe executive program 604 to convert binary numbers to decimal numberswhich are placed in designated storage locations.

3. Programmer's Console Package

The programmer's console programs are provided to facilitatecommunication with the P50 computer. Generally, the console packageprovides a means for loading programs into the computer, executingprograms, loading constants or instructions and dumping areas of mainand extended core memory. Core locations can be dumped in binary or tapeor in octal or a keyboard.

As already indicated, the programmer's console package operates withinthe priority structure of the executive program 604 and its elements aregenerally classified as a part of that program. After the programmer'sconsole package has been bid by depressing a programmer's consoleinterrupt button, the keyboard set is turned on and an input isrequested. An input consists of a two letter mnemonic followed either bya space and up to four constants or by a return. If more than twoletters precede the space or the return, only the last two letters areconsidered by the computer. The resulting two letter mnemonic iscompared to the defines mnemonics and if no mnemonic is found incorrespondence to the entered mnemonic and error is printed.

If the entered two letter mnemonic is equal to a stored mnemonic, atransfer to the proper program is made and if a space followed themnemonic code any constants preceding the return will be input. Thenumber of constants depends on the function being initiated. Constantsmay be entered in octal or decimal and a plus or minus sign preceding aconstant specifies it to be a decimal number while unsigned integers aretreated as being octal. Constants are terminated by a slash or by areturn.

If the correction character left parenthesis "(" is encountered, alldigits following the last slash or the space are ignored. If more thanfour constants are entered before a return, an error is printed and theprogrammer's console package turns the keyboard set off. If the numberof constants entered is different from that required by the functionbeing initiated, an error is printed and the keyboard set is turned off.

When a return is input to the programmer's console package, a transferis made to the particular console program requested with the constantsstored in the order in which they were input. When the programmer'sconsole program completes the requested activity further constants areentered in the same manner as the initial constants if they arerequired.

The programmer's console package in the executive program includes thefollowing programs:

1. Binary Load--Provides for loading a binary program tape through theprogrammer's console tape reader into main core.

2. Binary Punch--Causes the programmer's console punch to punch inbinary a core area or core location, a transfer code or a stop codedepending upon the number of input constants.

3. Check Tape--Provides for comparing a binary program tape with themain core contents on a word-by-word basis.

4. Numeric Load--Provides for making numeric entries into main memory.

5. Octal Dump--Provides for printing the contents of a core area oflocation in octal.

6. Run On Machine.

7. Set Limits--Provides for entry of alarm limits and the like.

8. Update Time--Provides for setting hours, minutes and seconds into thecomputer.

In addition, the programmer's console package includes an analog valueto engineering units conversion program considered subsequently inconnection with the log program.

4. Operator's Console Program

Flowcharts for the operator's console program are shown in FIGS. 27 and28. Generally, a depressed local operator's pushbutton causes a uniquesix bit code and a panel interrupt. The interrupt routine bids adominant level operator's console program represented by flowchart 624in FIG. 27. A similar flowchart (not shown) applies for the remotedirect wire control panel or for supervisory control.

The dominant level operator's console program first identifies the gasturbine or plant number and stores the contact closure input channelnumber for the local operator's panel associated with the identifiedturbine. The contact closure input channel includes six bits for thepushbutton code and eight bits for the thumbwheel switch input.

Determinations are then made as to whether generator breaker closing,line breaker closing or emergency shutdown has been requested. If so,immediate processing of the requested pushbutton control program isinitiated. If not, a flag corresponding to the associated turbine is setin the secondary sublevel program and it is put into the bidding state.

The operator's console secondary sublevel program is represented byflowchart 626 in FIG. 28. When the secondary sublevel program isexecuted, a check is made of the local panel flags under lockout todetermine whether any require processing. If a local panel flag has beenset, that flag is cleared, a turbine identifying number is registered,lockout is cleared and a jump is made to a local operator's readprogram. The associated contact closure input is again read and comparedwith the previous input and if it is the same a preprocessor block iscaused to pick up needed logical variables and a jump is made to theindividual pushbutton program required by the panel pushbuttonoperation. Generally, the pushbutton programs are associated with otherprogram blocks in the program system such as the sequencing program 600or the control program 602. If no local panel flags have been set, anexamination is made of the remote panel flags and if a remote panel flaghas been set action similar to that just described for the localpushbutton flag is initiated for the remote panel flag.

Generally, the pushbuttons cause bits to be set in three words for eachturbine in resident tables considered subsequently in connection withthe sequence program 600. Some pushbuttons, such as the LOCAL and REMOTEpushbuttons have flip-flop action and the associated pushbutton programsaccordingly run once and go to a final exit junction F. Otherpushbuttons cause a bit set only as long as the pushbutton is depressedso that after the pushbutton program is run, it exits through a recalljunction R. The F exit causes all bits in the operator's console bittable to be cleared except the flip-flop bits and then causes a jump toa program called STORE which post-processes and transfers the operator'sconsole bit table to the turbine resident tables used by the sequencingprogram 600. Lockout is then set and a jump is made to the beginning Sof the operator's console secondary sublevel program to determinewhether any other panel inputs need to be processed. The R exit causes arecall flag to be set and a jump to be made to the store program.

After all operator panel inputs have been processed, an examination ismade of the recall flags for each panel. If one of the recall flags isset, it is cleared, a common recall flag is decremented and a flag isset requesting the associated panel to be processed.

After all panel recall flags have been examined, the common recall flagis checked. If any operator panel inputs need to be reprocessed after ashort time delay, the common recall flag is not zero. In such case, thecommon recall flag is reset to zero and the program is put into timedelay after which the secondary sublevel program is restarted atjunction S. When the common recall flag is set at zero, the sublevelprogram is turned off.

It is noteworthy that the SELECT INDICATOR and SELECT DEVICE pushbuttonsare associated with programs used to load addresses into a table in theanalog output program 612 to indicate from an analog input tableassociated with the analog scan program 614 those values which are to bedisplayed on the various operator's panel instruments. The analog outputprogram 612 is subsequently considered more fully.

5. Analog Scan Program

Generally, the analog scan program provides an executive function inreading all analog points associated with the power plant 100 and anysimilar plant units. The frequency at which the analog points are readis determined by the needs of the process operation, and in thisinstance it is set at 30 points per second. The analog scan program canbe executed under hardware or software interrupt lockout.

The analog scan program 614 is arranged such that all points whichrequire reading within a predefined shortest time period are read withinthat period, and an appropriate fraction of other groups of analogpoints that must be read within longer periods are also read within theshortest time period. For example, slightly more than one-fifth of allinputs that require reading within a five second period are read duringthe same base period of one second.

The analog input system 308 (FIG. 12) includes a digital to analogconverter and a multiplexer circuit. After each converter cycle, aninterrupt starts the execution of the analog scan program 614. Allpoints set up during the last converter cycle are read and themultiplexer is set for the next group of points as soon as possibleafter the interrupt has been received. At the last input command, theconverter cycle is reinitiated and the necessary housekeeping andaddress modifying functions are performed to set up the input and outputcommands for the next converter interrupt.

For thermocouples, cold junction correction is added by the analog scanprogram before the value is stored in core. Thermocouple data processingis otherwise executed by the check program 616 or the control program. Aflowchart representation of the analog scan program 614 is shown in FIG.29. The following is a list showing the tables and words employed by theanalog scan program 614:

    __________________________________________________________________________    TABLE AND WORD DEFINITIONS                                                    __________________________________________________________________________      A table of multiplexer addresses (MXRTBL), ordered according to scan          frequencies (See                                                              FIG. 10-18). If there are N converters, the addresses are ordered in          groups of N with one                                                          point from each converter in each group, and ordered within the group         as converter 1, con-                                                          verter 2, and converter N. The multiplex address word is made up as           follows:                                                                    Bit  Meaning                                                                  __________________________________________________________________________    13   Indicates which set of offscale limits to use.                           12   Indicates gain setting to be used: a 1 indicates 5V scale, a 0                indicates 50 mV scale.                                                   11-6 Contain the multiplexer word to be output.                               5-2  Contain the number of the accumulator bit to be set (0-13.sub.10).       1-0  Indicate the multiplexer output channel to be used: 00 for chan-              nel 57, 01 for channel 37, 10 for channel 17, 11 for channel 77.         In a group, bits 5-0 of a multiplexer address word must be the same for       all converters - that                                                         is, the number of the bit to be output and the output channel must be the     same.                                                                           A word (NOSCAN) indicating the number of scan periods plus 1.                 A table (ANLTBL) of the number of points on each scan yet to be               processed.                                                                    A table (NPSPCT) of the number of points to be read on the basic period       for each scan                                                                 period.                                                                       A table (BLOCKF) giving the beginning address of the multiplexer words        for each scan.                                                                A table of processing words (PCW1TB, Processing Word 1) (see below)           which contains                                                                indices indicating the location of the value for each point. If the           value read is within in-                                                      strument limits, it is stored in the value location. If the value is          outside instrument limits,                                                    the previous value is left in the value location. This table is ordered       the same as the mul-                                                          tiplexer address table and is made up as follows:                           TABLE 10-2 - DATA WORD FORMATS FOR ANALOG SCAN (P50-SP12B-2)                  __________________________________________________________________________    Bit  Meaning                                                                  __________________________________________________________________________    13   Indicates operator delete for this point. The value will not be               updated as long as this bit is a 1.                                      12-10                                                                              Indicate thermocouples and cold junctions used or flow com-                   pensation required.                                                      9-0  Indicate the index for storing the value in the value                    __________________________________________________________________________         table.                                                               

6. Analog Output Program

As previously considered, the general approach employed for generatinganalog outputs is to employ external holding type operational amplifierswith the amplifier outputs measured by the computer through the analoginput system 308. The measured value is compared with the desired valueand the difference is employed in determining how long raise or lowercontact closure outputs must be closed to make the holding amplifierintegrate to the desired value. The raise or lower value is computed intenths of a second and it is determined by an element of the analogoutput program 612 which is run on a secondary level while the actualcontact closure output pulsing is performed by a pulser element of theanalog output program 612 run on a dominant level every tenth of asecond. The secondary level analog output program element is run everysecond for speed reference and load limit and every five seconds for theremaining outputs. FIG. 30A illustrates a flowchart representative ofthe dominant level pulser element 616 of the analog output program 612.Flowcharts 618 and 620 representative of the secondary sublevel analogoutput program element are shown in FIGS. 30B and 30C.

The pulser program employs a counter table having a highest address atlocation AOCTR. One counter is provided for each analog output and thetable is repeated for each turbine plant placed under control. Thepulser program examines each analog output counter and if it is zero theassociated raise and lower contact closure outputs are opened. If thecounter is positive it is decremented by one and the raise contactclosure output is closed. If the counter is negative, it is incrementedby one and the lower contact closure output is closed.

The raise and lower contact closure outputs appear in two contactclosure output registers and part of two other contact closure outputregisters for each turbine. The raise and lower contact closure outputsalways appear as adjacent bits with the lower contact closure outputbeing the odd-high bit. A macro AOM is defined which, in conjunctionwith a subroutine AOSUB, formulates and outputs one contact closureoutput word. The variables to be specified by each macro are determinedby a one bit mask indicating the lowest raise bit to the output, anumber indicating the number of adjacent analog contact closure outputpairs to be formulated, and bits and registers used in the contactclosure output call. The macro is repeated for each contact closureoutput word. The order of analog outputs in the counter tablecorresponds to the order of the register numbers in the macros and theorder of the bits in the individual contact closure output word.

After initialization, the secondary sublevel analog output programelement loads the counter table in three parts. First, the speedreference counters are loaded for all turbines. As observed in FIG. 20,these contact closure outputs are associated with an R-C delay in thehold integrator amplifier inputs, and an anticipation scheme is employedto take into account the energy stored in the capacitor. From thedifference in the program calculated and desired value and the measuredvalue for a speed reference output, there is subtracted any anticipatedadditional change as calculated the previous second. The error islimited to a value corresponding to a one second pulse. Half of theerror is saved as the anticipated change which would not yet haveoccurred by the next second, and the error is right shifted severaltimes and becomes the counter value.

Next, the fuel demand signal limit reference counters are loaded for allturbines. The count in this case is the difference between the desiredand the measured values right-shifted several times for count scaling.Finally, instrument analog outputs are processed next. The instrumentanalog outputs are scanned every five seconds so that one fifth of themare output each second for each turbine. To calculate the pulse countervalue, the desired value is added to an offset and the sum is multipliedby a constant. After shifting to the correct binary point, the measuredvalue is subtracted and the difference is right-shifted several timesfor count scaling.

The length of tables and loop counters is correctly adjusted for variousnumbers of turbines by setting NOMCH in the symbol table equal to thenumber of turbines. The length of the counter table (AOCTR), the desiredvalue address table (DVTB), and the speed reference anticipated changetable (ANTTB) vary with the number of turbines while the other countertables stay fixed in length. A desired value table DTTB contains theaddress of ASLP VALUE table locations which are to be output. Forinstruments, the desired value table is loaded by the operator's consoleprogram 606 and its order is also determined by this program.

A measured value table MVTB contains the addresses for turbine A of theASLP VALUE table locations which contain the last measured value of theanalog outputs. Because of interleaving in the ASLP VALUE table, theaddresses for the other turbines are determinable. A conversion offsettable COTB and a conversion slope table CSTB contain constants employedby the instrument analog output operations. A counter address tableCTATB is employed to reconcile the difference in order of handling theinstruments by the operator's console program 606 and the analog outputpulser element of the analog output program 612. A counter table AOCTRcontains the remaining time in tenths of a second that each integratorcontact closure output should be closed.

7. Sequencing Program a. Functional Philosophy

Generally, the sequencing program 600 is represented by a flowchartshown in FIG. 31 and it is run once every second to provide the plantsequencing operations required during turbine startup, to providecertain alarm detections and to provide sequencing for various planttasks during time periods other than the turbine startup time period. Asindicated by block 622, certain information regarding the status of theturbine plant 100 and other controlled plants is required for sequencingprogram execution. The required plant status information which isacquired includes continuous analog data and contact input closuresgenerated by operator panel switches, pressure switches, and other plantdevices. The acquired information is stored in a master logic table asindicated by the block 624. Next, in providing ultimately for betterplant startup management and better plant management generally, thestored data is employed in the evaluation of a plurality of blocks ofsequence logic as indicated by block 626.

The results of the evaluation of the sequence logic may requirecommunication with other programs in the program system in which eventthe results are stored for use by those programs. As indicated by block628, the results of the evaluation of the sequence logic may alsorequire certain contact closure outputs. In block 630, a resident tableof turbine data acquired from core memory by the acquisition block 622is saved in the original core memory location while nonresident turbinedata comprising operator panel inputs is allowed to be destroyed.

Block 632 then determines whether any additional turbines need to beprocessed in the current run of the sequencing program 600. If not, thesequencing program 600 is ended. If one or more gas turbines remain forsequencing logic determinations in the current run of the sequencingprogram 600, the program 600 is re-executed for the next turbine and theprocess is repeated until the last turbine has been serviced withsequence logic processing in the current sequencing program execution.

In FIG. 32, there is illustrated a data flow map for the sequencingprogram 600. As shown, there are four turbine data tables for therespectively designated gas turbines A, B, C and D. Each gas turbinedata table comprises a resident portion and a read only portion which isderived from the operator panel program 606. A preprocessor block 634corresponds to the block 622 shown in FIG. 31, and it obtains data fromanalog inputs, contact closure inputs, the resident turbine A table andthe read only turbine A table. The acquired data is stored in a masterlogic table as indicated by block 636 which corresponds to block 624 inFIG. 31. The master logic table 636 is employed in the execution oflogic program block 638 which corresponds to block 626 in FIG. 31.

After the sequence logic has been evaluated by the program 638 apostprocessor 640 is entered and it corresponds to blocks 628, 630 and632 in FIG. 31. Thus, contact closure outputs are generated and theturbine A resident table is saved. The postprocessor 640 then providesfor a repeat program execution for turbine B table data if a second gasturbine plant is under control. Similarly, repeat executions are made toprovide for entry and restorage of turbine C table data and turbine Dtable data if C and D gas turbine plants are under control. After thelast turbine sequence program execution has been completed, an exit ismade from the postprocessor block 640.

b. Sequencing Program Table Data Tables And Preprocess and PostprocessRoutine

The following information shows the core organization of the turbineresident read/write and read only tables, contact closure input andcontact closure output data tables, the master logic table and turbinealarm data tables. In addition, information on the contact closure inputroutines, analog input routines and contact closure output routinesemployed in the blocks 622 and 628 is included. A detailed programlisting employed in a specific application involves certain minorchanges from the following.

      TURBINE A RESIDENT BITS.sup.READ /WRITE WORD 13 12 11 10 9 8 7 6 5 4 3     2 1 0       10114 AUXRS L94 L86 ESTART NORSRT SYSR PEAK BASE MIN MODE4 MODE3 MODE2     MODE1 MODE0 10115 LOKOT1 L186 STRQ EMERG   P R E V I N      9 8 7 6 5 4     3 2 1 0 10116 SDLBC1 GBKROP RMPNH RMPNZ 66PNZ GAS OIL IGN PURGTD PURGE     SHTDWN 26CD FREEZ 5X 10117 HLBOTP EVPCOL BLVLV2BLVLV1 OLFNHI OILFNL     OILHTR CIROIL 39S L25 27L ATOSNC GBKRCL FBKRTP 10120 L4 OPX 88X LORSET     N14M10 VB2MIL 27B X L38 39R MIX 26E 26B SEQCK2 10121 66SFLSH6 FLSH5     FLSH4 FLSH3 FLSH2 FLSH1 ADJMIN XFER RUNSDN SDNSRT SDSORR VB4MIL VB3MIL     10122       SPARE    OLFNH2 SDNBL1 DSLBKR 10123       SPARE       TURBINE A RESIDENT TABLE (READ ONLY)OP,CONSOLE WORD 13 12 11 10 9 8 7     6 5 4 3 2 1 0       10124 43R 43L SSG 43STM 43STA HOLD5 HOLD4 HOLD3 HOLD2 HOLD1 43FT 43FM     43FO 43FG  REMOTE 10125 SSL 43LSR 43LSP 43LSB 43LSM NORSTP EMGSTP EMGSRT     FXFRPB 152LT 152LCR 52LCT 52LCL RESET 10126 SPARE1 SPARE2 SPARE3 SPARE4     70CL 70CR 43RM 43RA 65CL 65CR41TMN 41CMN 52GTMN 52GCMN 10127     SPARE   TURBINE B RESIDENT BITS.sup. READ /WRITE WORD 13 12 11 10 9 8 7     6 5 4 3 2 1 0       10244 AUXRS L94 L86 ESTART NORSRT SYSR PEAK BASE MIN MODE4 MODE3 MODE2     MODE1 MODE0 10245 LOKOT1 L186 STRQ EMERG   P R E V I N      9 8 7 6 5 4     3 2 1 0 10246 SDLBC1 GBKROP RMPNH RMPNZ 66PNZ GAS OIL IGN PURGTD PURGE     SHTDWN 26CD FREEZ 5X 10247 HLBOTP EVPCOL BLVLV2 BLVLV1 OLFNHI OILFNL     OILHTR GIROIL 39S L25 27L ATOSNC GBKRCL FBKRTP 10250 L4 OPX 88X LORSET     N14M10 VB2MIL 27B X L38 39R MIX 26E 26B SEQCK2 10251 66S FLSH6 FLSH5     FLSH4 FLSH3 FLSH2 FLSH1 ADJMIN XFER RUNSDN SDNSRT SDSORR VB4MIL VB3MIL     10252       SPARE     OLFNH2 SDNBL1 DSLBKR 10253       SPARE       TURBINE B RESIDENT TABLE (.sup.READ ONLY) OP. CONSOLE WORD 13 12 11 10 9      8 7 6 5 4 3 2 1 0       10254 43R 43L SSG 43STM 43STA HOLD5 HOLD4 HOLD3 HOLD2 HOLD1 43FT 43FM     43FO 43FGREMOTE 10255 SSL 43LSR 43LSP 43LSB 43LSM NORSTP EMGSTP EMGSRT     FXFRPB 152LT 152LCR 52LCT 52LCL RESET 10256 SPARE1 SPARE2 SPARE3 SPARE4     70CL 70CR 43RM 43RA 65CL 65CR 41TMN 41CMN 52GTMN 52GCMN 10257     SPARE  TURBINE C RESIDENT BITS.sup. READ /WRITE WORD 13 12 11 10 9 8 7 6 5      4 3 2 1 0       10374 AUXRS L94 L86 ESTART NORSRT SYSR PEAK BASE MIN MODE4 MODE3 MODE2     MODE1 MODE0 10375 LOKOT1 L186 STRQ EMERG   P R E V I N      9 8 7 6 5 4     3 2 1 0 10376 SDLBC1 GBKROP RMPNH RMPNZ 66PNZ GAS OIL IGN PURGTD PURGE     SHTDWN 26CD FREEZ 5X 10377 HLBOTP EVPCOL BLVLB2 BLVLV1 OLFNH1 OILFNL     OILHTR CIROIL 39S L25 27L ATOSNCGBKRCL FBKRTP 10400 L4 OPX 88X LORSET     N14M10 VBZMIL 27B X L38 39R MIX 26E 26B SEQCK2 10401 66S FLSH6 FLSH5     FLSH4 FLSH3 FLSH2 FLSH1 ADJMIN XFER RUNSDN SDNSRT SDSORR VB4MIL VB3MIL     10402       SPARE     OLFNH2 SDNBL1 DSLBKR 10403       SPARE       TURBINE C RESIDENT TABLE (.sup.READ ONLY) OP. CONSOLE WORD 13 12 11 10 9      8 7 6 5 4 3 2 1 0       10404 43R 43L SSG 43STM 43STA HOLD5 HOLD4 HOLD3 HOLD2 HOLD1 43FT 43FM     43FO 43FG  REMOTE 10405 SSL 43LSR 43LSP 43LSB 43LSM NORSTP EMGSTP EMGSRT     FXFRPB 152LT 152LCR 52LCT 52LCL RESET 10406 SPARE1 SPARE2 SPARE3 SPARE4     70CL 70CR 43RM 43RA 65CL 65CR 41TMN 41CMN 52GTMN 52GCMN 10407     SPARE  TURBINE D RESIDENT BITS.sup. READ /WRITE WORD 13 12 11 10 9 8 7 6 5      4 3 2 1 0       10524 AUXRS L94 L86 ESTART NORSRT SYSR PEAK BASE MIN MODE4 MODE3 MODE2     MODE1 MODE0 10525 LOKOT1 L186 STRQ EMERG   P R E V I N      9 8 7 6 5 4     3 2 1 0 10526 SDLBC1 GBKROP RMPNH RMPNZ 66PNZ GAS OIL IGN PURGTD PURGE     SHTDWN 26CD FREEZ 5X 10527 HLBOTP EVPCOL BLVLV2 BLVLV1 OLFNH1 OILFNL     OILHTR CIROIL 39S L25 27L ATOSNC GBKRCL FBKRTP 10530 L4 OPX 88X LORSET     N14MIO VB2MIL 27B X L38 39R MIX 26E 268 SEQCK2 10531 66S FLSH6 FLSH5     FLSH4 FLSH3 FLSH2 FLSH1 ADJMIN XFER RUNSDN SDNSRT SDSORR VB4MIL VB3MIL     10532       SPARE     OLFNHZ SDNBL1 DSLBKR 10533       SPARE       TURBINE D RESIDENT TABLE(.sup.READ ONLY) OP. CONSOLE WORD 13 12 11 10     9 8 7 6 5 4 3 2 1 0       10534 43R 43L SSG 43STM 43STA HOLD5 HOLD4 HOLD3 HOLD2 HOLD1 43FT 43FM     43FO 43FG  REMOTE 10535 SSL 43LSR 43LSP 43LSB43LSM NORSTP EMGSTP EMGSRT     FXFRPB 152LT 152LCR 52LCT 52LCL RESET 10536 SPARE1 SPARE2 SPARE3 SPARE4     70CL 70CR 43RM 43RA 65CL 65CR 41TMN 41CMN 52GTMN 52GCMN 10537     SPARE  CCI BIT# 13 12 11 10 9 8 7 6 5 4 3 2 1 0            639GL 639GH 639GI      Gas Gas Gas Channel 21     Pressure     Pressure Supply * * * * * * *      Low High Pressure        Switch     639DT L6382 L6381 43PSG L634 L631 L633 L637 639D L6310  43SR L6311   Oil     Pres. Pressure Switches and of Bearing Bearing High Overspd. Flow     Compress  69SRO Instrum.   Main Valve 2 Valve 1 Pres. Test Oil Pres. Oil     Pres. Lube Trip Oil Divider Inlet  Safe Air Pres. Channel 22 * Pump     Closed* Closed* Switch Switch* Switch* Oil Pressure Outlet 2 Pressure *     Run* Switch*   Inlet-   (Auto)*   Pressure* Switch* Pressure* Switch*     Alm,   XFER   to DC*   27DC 27D 27A L332 L331  L711 45F2 45F1 L2619 L636     639G2 639DS   Loss of DC Cntrl AC Inlet Inlet  Float Sw. Fire Fire High     Combustor Isolation Oil Pres. Channel 23  DC to Under- Under- Guide     Guide * Oil Detectors Detectors Disc Shell Valve Fuel   Aux. Voltage*     Voltage* Vane Vane  Reservoir #2* #1* Cooling Pressure Diaphragm Pump     Oil   Closed* Open*  Low*   Air Ign. Sw.* Pressure Inlet*   Pump     Temp.*  Switch*  43MC 88TGA 52LA  41A 52GA       70AP  and Aux. Line     Field Generator       Volt. Adj. Channel 24 Contacts Contact Breaker *     Breaker Breaker ** * * * * Rheo. in *  Motor T.G. A Contact*  A Contact*     A Contact*      Preset  Cntri Line           Start  Cnt* Strter*       Posn.*         18T 18A 43SM 43SD 52MA L49 37L         Diesel Starting     Start Manual Start Guard- Low Speed Channel 25 * *      Trip Motor     Motor* Sw- Motor ISTOR Starting         Contact* Bkr.  Start Bkr. on     Start Current          Closed*  Device Closed Motor Detector     Mt.*           86G Channel 26 * * * * * * * * * Lockout * * * *      Generator*        FD7B FD7A FD6B FD6A Channel 27       Flame Flame     Flame Flame        Detectors Detectors Detectors Detectors     *(available as switches)

INCCI CCI Pre-Processor Routine

In order to minimize the amount of wasted space in the master datatable, only the occupied bits of each CCI channel (including anyunoccupied bits which might be between the first and last occupied bits)are unpacked into the CCI data area of the master data table. In thissection an occupied bit is one which is of interest to the sequencingprogram. An unoccupied bit, on the other hand, is one which is of nointerest to the logic program. When unoccupied bits are encounteredbetween the first and last occupied bits of a CCI channel, a dummy value(OCT 0) is loaded into the corresponding location of the CCI data table.

The unoccupied bits which are located between the first and lastoccupied bits of a CCI channel are represented in the CCI data tablebecause it is more efficient to unpack one sequential string of bits(the string possibly containing several unused bits) for each channelthan to unpack only the bits which are of interest to the logic program.

The following example shows the method used to transmit the data on CCIchannels to the CCI data area of the master data table. ##SPC1##

ANALOG INPUT ROUTINE

Define the following with EQU cards:

A. This table of EQU cards defines an address in the ASLP (analog signallist) which is related to each of the analog inputs.

These addresses are calculated by multiplying the index number of theinput (corresponding to a one turbine system) by the number of units inthe system. The resulting value is an address relative to the beginninglocation of the ASLP for the first turbine. To find the desired address,add the beginning location of ASLP which has been defined as VALUE plusone less than the number of turbines (See below). Remember that theaddresses below correspond to turbine A only.

The addresses are used to construct a table which is used by the analoginput routine. Below is a typical table.

    __________________________________________________________________________    CSOIND8EQU 56*NTURB+VALVE+NTURB-1                                             27BIN 8EQU 114*NTURB+VALUE+NTURB-1                                            LT35IN 8EQU 13*NTURB+VALUE+NTURB-1                                            27LIN 8EQU 114*NTURB+VALUE+NTURB-1                                            LT17IN 8EQU 0*NTURB+VALUE+NTURB-1                                             LT18IN 8EQU 1*NTURB+VALUE+NTURB-1                                             LT19IN 8EQU 2*NTURB+VALUE+NTURB-1                                             LT20IN 8EQU 3*NTURB+VALUE+NTURB-1                                             LT21IN 8EQU 4*NTURB+VALUE+NTURB-1                                             LT22IN 8EQU 5*NTURB+VALUE+NTURB-1                                             LT23IN 8EQU 6*NTURB+VALUE+NTURB-1                                             LT24IN 8EQU 7*NTURB+VALUE+NTURB-1                                             LT25IN 8EQU 15*NTURB+VALUE+NTURB-1                                            LT26IN 8EQU 16*NTURB+VALUE+NTURB-1                                            LT30IN 8EQU 11*NTURB+VALUE+NTURB-1                                            LT33IN 8EQU 12*NTURB+VALUE+NTURB-1                                            LT36IN 8EQU 14*NTURB+VALUE+NTURB-1                                            DC12IN 8EQU 32*NTURB+VALUE+NTURB-1                                            DC22IN 8EQU 33*NTURB+VALUE+NTURB-1                                            DC32IN 8EQU 34*NTURB+VALUE+NTURB-1                                            DC42IN 8EQU 35*NTURB+VALUE+NTURB-1                                            LT27IN 8EQU 42*NTURB+VALUE+NTURB-1                                            LT28IN 8EQU 43*NTURB+VALUE+NTURB-1                                            LT29IN 8EQU 44*NTURB+VALUE+NTURB-1                                            39V11N 8EQU 45*NTURB+VALUE+NTURB-1                                            39V2IN 8EQU 46*NTURB+VALUE+NTURB-1                                            39V3IN 8EQU 47*NTURB+VALUE+NTURB-1                                            39V4IN 8EQU 50*NTURB+VALUE+NTURB-1                                            DC11IN 8EQU 71*NTURB+VALUE+NTURB-1                                            DC21IN 8EQU 72*NTURB+VALUE+NTURB-1                                            DC31IN 8EQU 73*NTURB+VALUE+NTURB-1                                            DC41IN 8EQU 74*NTURB+VALUE+NTURB-1                                            ASPIND 8EQU 101*NTURB+VALUE+NTURB-1                                           ASPBCK 8EQU 102*NTURB+VALUE+NTURB-1                                           AKWATT 8EQU 103*NTURB+VALUE+NTURB-1                                           ACOMBR 8EQU 117*NTURB+VALUE+NTURB-1                                           ASPREF 8EQU 120*NTURB+VALUE+NTURB-1                                           __________________________________________________________________________      Using LT30 as an example:                                                     (a) if NTURB = 1; LT30IN = 11.sub.8 + VALUE + 1 - 1                           LT30IN is the ASLP address for LT30 corresponding to turbine A in a one       unit                                                                          system.                                                                       (b) if NTURB = 2; LT30IN = 22.sub.8 + VALUE + 2 - 1                           LT30IN is the ASLP address for LT30 corresponding to turbine A in a two       unit                                                                          system.                                                                       (c) if NTURB = 3; LT30IN = 33.sub.8 + VALUE + 3 - 1                           LT30IN is the ASLP address for LT30 corresponding to turbine A in a           three unit                                                                    system.                                                                       (d) if NTURB = 4; LT30IN = 44.sub.8 + VALUE + 4 - 1                           LT30IN is the ASLP address for LT30 corresponding to turbine A in a           four unit                                                                     system.                                                                       Using ASPREF as an example:                                                   (a) if NTURB = 1; ASPREF = 120.sub.8  + VALUE + 1 - 1                         (b) if NTURB = 2; ASPREF = 240.sub.8 + VALUE + 2 - 1                          (c) if NTURB = 3; ASPREF = 360.sub. 8 + VALUE + 3 - 1                         (d) if NTURB = 4; ASPREF = 500.sub.8 + VALUE + 4 - 1                          If turbine B, C, or D is being considered, a respective value of 1, 2,        or 3 must be sub-                                                             tracted from the index calculated for turbine A. The analog input             routine subtracted                                                            the correct amount from the turbine A index if turbine B, C, or D is          being considered                                                              rather than turbine A.                                                        NTURB - the number of turbines in the system (1,2,3, or 4), NTURB must        be defined                                                                    before the correct index of an analog value can be determined. Thus,          the value of the                                                              ASLP address of an analog input is dependent upon NTURB.                    II.                                                                             Certain tables are required by the analog input routine.                    A.                                                                              As ASLP address table (IDXTBL) which consists of an address (depending        upon NTURB)                                                                   for each of the analog input values. Remember that all of these               addresses correspond to                                                       turbine A. This table must be in the same order as the destination            table which will be                                                           discussed shortly. The ASLP address table is constructed using the            symbols in Section I,                                                         part A. This table follows the analog input routine directly in the           sequence program.                                                             Typical ASLP address table.                                                 IDXTBL OCT LT30IN                                                             OCT LT33IN                                                                    OCT LT36IN                                                                    OCT DC11IN                                                                    OCT DC21IN                                                                    OCT DC31IN                                                                    OCT DC41IN                                                                    OCT LT27IN                                                                    OCT LT28IN                                                                    OCT LT29IN                                                                    OCT 39V1IN                                                                    OCT 39V2IN                                                                    OCT 39V3IN                                                                    OCT 39V4IN                                                                    OCT DC12IN                                                                    OCT DC22IN                                                                    OCT DC32IN                                                                    OCT DC42IN                                                                    OCT ASPIND                                                                    OCT ASPBCK                                                                    OCT AKWATT                                                                    OCT ACOMBR                                                                    OCT ASPREF                                                                    OCT 38DIDX                                                                      TBLEND SYN L-1                                                              B.                                                                              Once the value of a particular analog input has been picked up from the       ASLP table, it is                                                             stored in a destination table (see below). This destination table is          used as an analog input                                                       information center by the sequencing. This destination table must be in       the same order                                                                as the ASLP address table (Section II, part A).                               The following are the Analog Input values used by the Logic Program.          Order must be,                                                                same as IDXTBL.                                                             __________________________________________________________________________                                           (Binary point,                                                                engineering units)                     FULIND                                                                              OCT FUEL INDICATOR-CSO           (6,V)                                  27B   OCT DEAD BUS                     (6,V)                                  27L   OCT DEAD LINE                    (6,V)                                  LT35  OCT INLET MANIFOLD FUEL PUMP     (0,F)                                  LT17  OCT GEAR BEARING DRAIN (GEN. END)                                                                              (0,F)                                  LT18  OCT GEAR BEARING DRAIN (TURB END)                                                                              (0,F)                                  LT19  OCT PINION BEARING DRAIN (GEN. END)                                                                            (0,F)                                  LT20  OCT MAIN GEAR DRAIN              (0,F)                                  LT21  OCT PINION BEARING DRAIN (TURB END)                                                                            (0,F)                                  LT22  OCT COMPRESSOR JOURNAL BEARING BAB.                                                                            (0,F)                                  LT23  OCT THRUST BEARING SHOE BAB.     (0,F)                                  LT24  OCT TURBINE BEARING BAB.         (0,F)                                  LT25  OCT GENERATOR BEARING DRAIN (TURB END INBRD.)                                                                  (0,F)                                  LT26  OCT GENERATOR BEARING DRAIN (EXCITER END)                                                                      (0,F)                                  LT30  OCT COMPRESSOR DISCHARGE TEMPERATURE                                                                           (0,F)                                  LT33  OCT COMPRESSOR INLET TEMPERATURE (0,F)                                  LT36  OCT GEAR SUPPORT METAL TEMPERATURE                                                                             (0,F)                                  DC11  OCT DISC CAVITY                  (0,F)                                  DC21  OCT DISC CAVITY                  (0,F)                                  DC31  OCT DISC CAVITY                  (0,F)                                  DC41  OCT DISC CAVITY                  (0,F)                                  LT27  OCT LUB OIL RES. TEMP. CNTRLS COOLER FAN                                                                       (0,F)                                  LT28  OCT LUB OIL RES. TEMP HTR CNTRLS AND MIN TEMP                                                                  (0,F)                                  LT29  OCT LUBE OIL TEMPERATURE         (0,F)                                  39V1  OCT VIBRATION COMPRESSOR BEARING (6,MIL)                                39V2  OCT VIBRATION-TURBINE BEARING    (6,MIL)                                39V3  OCT VIBRATION-GEN. INBOARD BEARING                                                                             (6,MIL)                                39V4  OCT VIBRATION-GEN. OUTBOARD BEARING                                                                            (6,MIL)                                DC12  OCT DISC CAVITY                  (0,F)                                  DC22  OCT DISC CAVITY                  (0,F)                                  DC32  OCT DISC CAVITY                  (0,F)                                  DC42  OCT DISC CAVITY                  (0,F)                                  14M   OCT MAIN SPEED CHANNEL           (3,PERCENT)                            14A   OCT AUX. SPEED CHANNEL           (3,PERCENT)                            KW    OCT KILOWATT                     (6,MW)                                 COMBR OCT COMBUSTOR SHELL PRESSURE     (3,PSG)                                D14R  OCT SPEED REFERENCE              (3, PERCENT)                           __________________________________________________________________________     ##SPC2##

    __________________________________________________________________________     ##STR3##                                                                      ##STR4##                                                                      ##STR5##                                                                      ##STR6##                                                                      ##STR7##                                                                      ##STR8##                                                                      ##STR9##                                                                     __________________________________________________________________________    TABLE OF ANALOG VALUES                                                                                             Logic                                    Mnemonic     Location     Index      Mnemonic                                 __________________________________________________________________________    ALT30        23411        11         LT30                                     ALT33        23412        12         LT33                                     ALT36        23414        14         LT36                                     A1DC11       23432        32         DC11                                     A1DC21       23433        33         DC21                                     A1DC31       23434        34         DC31                                     A1DC4        23435        35         DC41                                     ALT27        23442        42         LT27                                     ALT28        23443        43         LT28                                     ALT29        23444        44         LT29                                     A39V1        23445        45         39V1                                     A39V2        23446        46         39V2                                     A39V3        23447        47         39V3                                     A39V4        23450        50         39V4                                     A1DC12       23471        71         DC12                                     A1DC22       23472        72         DC22                                     A1DC32       23473        73         DC32                                     A1DC42       23474        74         DC42                                     ASPIND       23501        101        14M                                      ASPBCK       23502        102        14A                                      AKWATT       23503        103        KW                                       ACOMBR       23517        117          COMBR                                  ASPREF       23520        120        D14R                                     __________________________________________________________________________     ##STR10##                                                                     ##STR11##                                                                     ##STR12##                                                                     ##STR13##                                                                     ##STR14##                                                                     ##STR15##                                                                     ##STR16##                                                                    __________________________________________________________________________    PRELOG. . .                                                                   Logic Pre-Processor                                                           Upon entry into PRELOG routine, the beginning address of the turbine          resident table                                                                (address depends on the turbine specified) must be in the accumulator.         ##STR17##                                                                    Pick up the whole word data from the turbine resident table (first            113.sub.8 locations) and                                                      transfer it to the whole word portion of the sequencing data area (first      113.sub.8 locations). Contents                                                of location one of resident table is transferred to contents of location      one of sequencing data area.                                                  Continue sequentially until all 113.sub.8 pieces of whole word data has       been transferred.                                                              ##STR18##                                                                    Next, pick up the 12 packed words of data from turbine resident table.        These 12 words                                                                follow the whole word portion of the resident table. Unpack these 12          words into the packed word                                                    portion of the sequencing data area in the following manner:                  __________________________________________________________________________     ##SPC3##

    ______________________________________                                         MASTER LOGIC TABLE                                                           ______________________________________                                        IMAGE OF TURBINE RESIDENT TABLE                                               (SEQUENCING DATA AREA)                                                        READ ONLY AREA - LOGIC INPUTS SET                                             BY OPERATOR PANEL PROGRAM                                                     CCI'S (WHOLE WORD)                                                            CCO'S (WHOLE WORD)                                                            ANALOG INPUT VALUES                                                           LOCAL VARIABLES                                                               (WHOLE WORD-SET BY LOGIC PROGRAM)                                             LOGIC PARAMETERS, CHECK LIMITS, ETC.                                          ______________________________________                                        TURBINE RESIDENT TABLE                                                        ______________________________________                                        BEGINNING ADDRESS OF TABLE, TURBINE                                           NUMBER, HIGH CCI CHANNEL NUMBER AND                                           HIGH CCO REGISTER NUMBER OF TURBINE                                           IDENTIFIED BY TURBINE NUMBER.                                                 HOUR TIME DELAYS (3 WORDS/DELAY)                                              SECOND TIME DELAYS (2 WORDS/DELAY)                                            COUNTERS                                                                      ELAPSED HOUR TABLES FOR OPERATION MODES                                       ALARM TABLES (PACKED BITS)                                                    SEVEN PACKED WORDS (READ/WRITE)                                               ONE SPARE PACKED WORD                                                         THREE PACKED WORDS (READ ONLY)                                                ONE SPARE PACKED WORD                                                         ______________________________________                                    

    ALARM TABLE       BIT# 14 13 12 11 10 9 8 7 6 5 4 3 2 1       TURBINE A  14 1312 11 10 9 8 7 6 5 4 3 2 1 10100 SPD 69SR L636 LT28     EXHT/C SEQ SEQ SEQ OPEN FLME FLME FLME FLME FLME  REF HI PERM HI LO FAIL     CK4 CK1 CK3 T/C SHTDWN 7B 7A 6B 6A  28 27 26 25 24 23 22 21 20 19 18 17     16 15 10101 26ED 26BD 331 332 BLVLV2 BLVLV1 639GL 639GH 70AP VIB 43SD/     41A 43PSG 43MC  TMP TMP NOT CL NOT OP OPEN OPEN GAS GAS FAIL SHTDWN 43SM     CLOSED PERMPERM  42 41 40 39 38 3736 35 34 33 32 31 30 29 10102 BLVLV1     BLVLV1 27DC LO-ATM LOSS NOT 639DS FRI/2 VB3 VB4 2619 27D 637 L631     CLOSED CLOSED OLAX AIR STRT DEV ON TG LO FIRE ALM IN ALM EX HI LO CHG     OVSPD LUBE  56 55 54 53 52 51 50 49 48 47 46 45 44 43 10103 DC3 DC3 DC2     DC2 DC1 DC1 6311 LT29 711 6310 VB1 VB2 639D 639D  SHDWN ALM SHDWN ALM SH     DWN ALM AIRLO LUB HI RES LO SUCT ALM GN ALM EX LO HI  70 69 68 67 66 65     64 63 62 61 60 59 58 57 10104 GEN GEN BUS 81B LT36-LT33 60CFVB TRANS INV     XFR FL PUMP XMR DC4 DC4  LOCKOUT GR1 GR2 GRD 27B >70° F.  FAIL     XFR TO OIL XFR RLY 61 SHDWN ALM  84 83 82 81 80 79 78 77 76 75 74 73 72     71 10105 LT17 LT18 LT19 LT20 LT21 LT22 LT23 LT24 LT25 LT26 26BA 26EA 27A     LT35  BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI TMP     TMP LO CHG HI       TURBINE B  14 13 12 11 10 9 8 7 6 5 4 3 2 1 10230 3PD 69SR L636 LT28     EXHT/C SEQ SEQ SEQ OPEN FLME FLME FLME FLME FLME  REF HI PERM HI LO FAIL     CK4 CK1 CK3 T/C SHTDWN 7B 7A 6B 6A  28 27 26 25 24 23 22 21 20 19 18 17     16 15 10231 26ED 26BD 331 332 BLVLV2 BLVLV1 639GL 639GH 70AP V1B 43SD/     41A 43PSG 43MC  TMP TMP NOT CL NOT OP OPEN OPEN GAS GAS FAIL SHTDWN 43SM     CLOSED PERM PERM  42 41 40 39 38 37 36 35 34 33 32 31 30 29 10232 BLVLV2     BLVLV1 27DC LO-ATM LOSS NOT 639DS FRI/2 VB3 VB4 2619 27D 637 L631     CLOSED CLOSED OLAX AIR STRT DEV ON TG LO FIRE ALM IN ALM EX HI LO CHG     OVSPD LUBE  56 55 54 53 52 5150 49 48 47 46 45 44 43 10233 DC3 DC3 DC2     DC2 DC1 DC1 6311 LT29 711 6310 VB1 VB2 639D 639D  SHDWN ALM SHDWN ALM SH     DWN ALM AIRLO LUB HI RES LO SUCT ALM GN ALM EX LO HI  70 69 68 67 66 65     64 63 62 61 60 59 58 57 10234 GEN CEN GEN BUS 81B LT36-LT33 60CFVB TRANS     INV XFR FL PLUMP XMR DC4 DC4  LOCKOUT GR1 GR2 GRD 27B >70° F.     FAIL XFR TO OIL XFR RLY 61 SHDWN ALM  84 83 82 81 80 79 78 77 76 75 74     73 72 71 10235 LT17 LT18 LT19 LT20 LT21 LT22 LT23 LT24 LT25 LT26 26BA     26EA 27A LT35  BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI     BRGHI TMP TMP LO CHG HI       TURBINE C  14 13 12 11 10 9 8 7 6 5 4 3 2 1 10360 SPD 69SR L636 LT23     EXHT/C SEQ SEQ SEQ OPEN FLME FLME FLME FLME FLME  REF HI PERM HI LO FAIL     CK4 CK1 CK3 T/C SHTDWN 7B 7A 6B 6A  28 27 26 25 24 23 22 21 20 19 18 17     16 15 10361 26ED 26BD 331 332 BLVLV2 BLVLV1 639GL 639GH 70AP V18 43SD/     41A 43PSG 43MC  TMP TMP NOT CL NOT OP OPEN OPEN GAS GAS FAIL SHTDWN 43SM     CLOSED PERM PERM  42 41 40 39 38 37 36 35 34 33 32 31 30 29 10362 BLVLV2     BLVLV1 27DC LO-ATM LOSS NOT 639DS FR1/2 VB3 VB4 2619 27D 637 L631     CLOSED CLOSED OLAX AIR STRT DEV ON TG LO FIRE ALM IN ALM EX HI LO CHG     OVSPD LUBE  56 55 54 53 52 51 50 49 48 47 46 45 44 43 10363 DC3 DC3 DC2     DC2 DC1 DC1 6311 LT29 711 6310 VB1 VB2 639D 639D  SHDWN ALM SHDWN ALM SH     DWN ALM AIRLO LUB HI RES LO SUCT ALM GN ALM EX LO HI  70 69 68 67 66 65     64 63 62 61 60 59 58 57 10364 GEN GEN GEN BUS 81B LT36-LT33 60CFVB TRANS     INV XFR FL PUMP XNR DC4 DC4  LOCKOUT GR1 GR2 GRD 27B >70° F.     FAIL XFR TO OIL XFR RLY 61 SHDWN ALM  84 83 82 81 80 79 78 77 76 75 74     73 72 71 10365 LT17 LT18 LT19 LT20 LT21 LT22 LT23 LT24 LT25 LT26 26BA     26EA 27A LT35  BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI     BRGHI TMP TMP LO CHG HI       TURBINE D 14 13 12 11 10 9 8 7 6 5 4 3 2 1 10510 SPD 69SR L636 LT28     EXHT/C SEQ SEQ SEQ OPEN FLME FLME FLME FLME FLME  REF HI PERM HI LO FAIL     CK4 CK1 CK3 T/C SHTDWN 7B 7A 6B 6A  28 27 26 25 24 23 22 21 20 19 18 17     16 15 10511 26ED 26BD 331 332 BLVLV2 BLVLV1 639GL 639GH 70AP V18 43SD/     41A 43PSG 43MC  TMP TMP NOT CL NOT OP OPEN OPEN GAS GAS FAIL SHTDWN 43SM     CLOSED PERM PERM  42 41 40 39 38 37 36 35 34 33 32 31 30 29 10512 BLVLV2     BLVLV1 27DC LO-ATM LOSS NOT 639DS FRI/2 VB3 VB4 2619 27D 637 L631     CLOSED CLOSED OLAX AIR STRT DEV ON TG LO FIRE ALM IN ALM EX HI LO CHG     OVSPD LUBE  56 55 54 53 52 51 50 49 48 47 46 45 44 43 10513 DC3 DC3 DC2     DC2 DC1 DC1 6311 LT29 711 6310 VB1 VB2 639D 639D  SHDWN ALM SHDWN ALM SH     DWN ALM AIRLO LUB HI RES LO SUCT ALM GN ALM EX LO HI  70 69 68 67 66 65     64 63 62 61 60 59 58 57 10514 GEN GEN GEN BUS 81B LT36-LT33 60CFVB TRANS     INV XFR FL PUMP XMR DC4 DC4  LOCKOUT GR1 GR2 GRD 27B >70° F.     FAIL XFR TO OIL XFR RLY 61 SHDWN ALM  84 83 82 81 80 79 78 77 76 75 74     73 72 71 10515 LT17 LT18 LT19 LT20 LT21 LT22 LT23 LT24 LT25 LT26 26BA     26EA 27A LT35  BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI BRGHI     BRGHI TMP TMP LO CHG HI     ##SPC4##

      CCO BIT # 13 12 11 10 9 8 7 6 5 4 3 2 1 0        52GT 52GC 52MT 52MC 2829D Start Combustor 202A 31X   41T 41C   Gen.     Gen. Start Start Diesel Diesel* Shell Overspd. Ignition   Field Field     Register 0 Bkr. Bkr. Motor Motor Trip  Pressure Trip Relay*   Bkr. Bkr.     Trip Close Bkr. Bkr. Contact*  Solenoid* Solenoid    Trip Close    Trip     Close    Valve*    Output Output  HOLDLP    SYSRLP   PEAKLP BASELP MINLP       GBKRLP FBKRLP Register 1 Hold    System   Peak Base Min.   Gen. Field     Lamp    Reserve   Lamp Lamp Lamp   Bkr. Bkr.      Lamp        Lamp Lamp     FLONLP IGNLP OSTPLP OSTVLP BRPSLP SDEVLP AXPONL TGONLP LBPSLP MCONLP     TTRLP AXRSLP  Fuel Ignition Overspd Overspd Bearing Start Aux. Turning     Lube Master Turbine Aux. Register 2 On Lamp Trip Trip Oil Device Pump     Gear Oil Contact Trips Reset  Lamp  Press. Valve Press. On On On Press.     On Reset Lamp    Lamp Lamp Lamp Lamp Lamp Lamp Lamp Lamp Lamp  GSNLP     SPNLP NSPLP ESPLP GENTRL   SNCSPL RTSLP BVCLDL FLMC7L FLMC6L  Gas Spin     Normal Emerg. Generator   Sync. Ready Bleed Flame Flame Register 3     Supply Lamp Stop Stop Trip   Speed To Valves Detector Detector  Normal     Lamp Lamp Lamp   Lamp Start Closed 7 Lamp 6 Lamp  Lamp        Lamp Lamp     L2017 L20102 L20101 201D 203B 201G L2035 SDNLP  ESRTLP  XFRLP MIXLP     GASLP  AMARSL Compr. Compr. Oil Gas Gas C2035 Shut  Emerg.  XFER Mix Gas     Register 4 Atomizer Bleed Bleed IsolationBlow-Isolation Inst. Air Down     Start  Lamp Lamp Lamp  Air Solen. Valve Valve Valve* down Valve*     Solenoid* Lamp  Lamp   Solen. Solen.  Valve*   #2 #1*    88EC 88VE 88CP     73LHX 88LCL 88LCH 88ALX 88TC2 88TC1 88TG 88TPD 88TPA    Evap. Vapor     88CPX Lube 88CLX 88CHX Aux. Turbine Air Turning Fuel Pumps Register 5     Cooler* Extractor* Lube Oil Oil Lube Oil Cool Fan Lube Cooler Fans Gear*     XFER AC*      Circ. Heater* Low* High* Pump #2* #1*  DC*      Pump*     Lines-          Starter*     *(available as lamps)

c. Plant Sequence Functions

Generally, the sequence control subsystem embraces certain logicoperations which provide for an orderly advance of the process throughstartup, run and shutdown operations while providing many operatingadvantages. In providing sequence operations, the sequence controlsubsystem includes the sequencing program which interacts with thecontrol program and with plant devices to provide direction to processevents and simultaneously to provide plant and turbine protection.

The plant sequence functions associated with startup of the gas turbine104 to operate the power plant 100 have previously been generallyconsidered in connection with the startup chart shown in FIG. 18. In thestartup process, a programmed computer master contactor function andoperation selectors are employed to force the sequence of starting andoperation to assure that turbine startup will normally take place over afixed predefined time interval for the reasons previously considered.For plant startup to be enabled, certain plant conditions must exist.

Thus, the software master contactor serves to establish and disestablishlogic conditions necessary for initiating the making and braking ofexternal control circuits for equipment startup and shutdown operationsunder predetermined plant and equipment conditions. All maintenance andtransfer switches including the following must be in the correctposition for starting:

    ______________________________________                                        Motor Control Center                                                                           Pressure Switch & Gauge Cabinet                              (43 MC)          (43 PSG)                                                     ______________________________________                                        Diesel Heater    Ignition                                                     Lube Oil Reservoir                                                                             Overspeed Trip                                               Instrument Air   Isolation Gas                                                Turbine Cooling Air #1                                                                         Isolation Oil                                                Turbine Cooling Air #2                                                                         Instrument Air Isolation                                     Vapor Extractor                                                               Lube Oil Cooler - Low                                                         Lube Oil Cooler - High                                                        Atomizing Air                                                                 Auxiliary Lube Pump                                                           Lube Oil Circulating Pump                                                     Fuel Transfer Pump AC                                                         Fuel Transfer Pump DC                                                         ______________________________________                                    

In addition, the turbine unit speed must be below 10% rated speed, thefield breaker must be correctly positioned and all turbine malfunctionsmust be corrected. When the turbine unit is available for startup, theTURBINE AUX RESET and TURBINE TRIP RESET sequence lamps are lit and athird lamp READY TO START is lit if both of the reset lamps are lit.

Other conditions which should be preset include the closing of allassociated control and service breakers as well as AB breakers whichsupply power to motor circuits. If the computer system 305 had beendeenergized, the computer breakers must be closed and the computer mustbe started and the time of day entered. All alarm conditions must beacknowledged and lockout relays reset. A remote or local operator'scontrol selection also must be made.

More prestart checks include;

1. At least one of each pair of flame detector contacts open.

2. Oil reservoir not too cold.

3. Speed reference & fuel demand signals in proper range.

4. Safe run switch on PSGC positioned properly.

5. Voltage regulator motor operated rheostats (voltage adjust & base) inpreset start position.

6. Dead computer system reset & 48V CCI detection voltage sourceavailable.

Under local control, the LOAD MINIMUM or LOAD BASE or LOAD PEAK orEMERGENCY START pushbutton can be used to initiate a gas turbinestartup. A master contactor function is then enabled to cause anauxiliary lubrication pump starter to be energized and an instrument airsolenoid valve 20-35 (IEEE) to be opened. In addition, a combustor shellpressure transducer line drain solenoid valve 20-25 (IEEE) is closed andthe AC or DC fuel transfer pump is energized. After the auxiliarylubrication pump builds up sufficient pressure to operate a pressureswitch 63-4 (IEEE), a starter for the turning gear is operated. Thirtyseconds are allowed by a timer 62Q (IEEE) for lubrication pressure tobuild up or the turbine unit is shut down. The sequence is continued ifthe turning gear line starter is operated. Next, the master contactorfunction enables startup operations for the starting engine 126 iflubrication oil pressure causes the operation of a pressure switch 63-1(IEEE).

At about 15% rated speed, the turning gear motor is desirably turnedoff. However, it may be kept on to a higher speed such as 50% to keepthe diesel on where diesel seal in is not used. At firing speed assensed by an axial compressor pressure switch 63-6 (IEEE), a turbineoverspeed trip solenoid 20-2A (IEEE) and under pneumatic control, a ventsolenoid 20-3B (IEEE) are energized to reset. With adequate buildup ofoverspeed trip solenoid oil pressure, a pressure switch 63-7 (IEEE) isclosed to allow ignition.

The ignition sequence includes energizing the ignition transformer andsetting the fuel control circuits as determined from the mode of fuelselected by the operator. A selectable time period, in this case 30seconds is allowed for establishing flame in both detected combustorbaskets or, after three ignition attempts with appropriate purge times,the unit is shut down. An ignition timing function allows certainpredetermined purge time between successive ignition attempts. Atomizingair flow is initiated as required for liquid or oil fuel supply.

At approximately 60% rated speed, shutdown of the starting engine 126 isinitiated. As successive predetermined combustor shell pressures aredetected near synchronous speed, the respective bleed valves are closed.

During the time period from the ignition to synchronous operation, thecontrol system 300 is placed in the Mode 1 operation and the gas turbinespeed reference is increased in a program controlled nonlinear manner todetermine the fuel valve positioning. With the compressor inlettemperature at 80° F., the desired acceleration is achieved with theturbine inlet temperature limited to 1200° F. for a normal start and1500° F. for an emergency start.

When the turbine has been advanced to idle (or top or synchronous)speed, it is ready to be synchronized and the control system 300 istransferred to Mode 2 operation in which either manual or automaticsynchronizing is performed following field breaker closure. When theturbine-generator unit is synchronized and the generator breaker isclosed, the control system 300 is transferred to Mode 3 or Mode 4operation and the speed reference is set at a value of 106% rated speed.Load is ramped to a predetermined level at a predetermined rate underprogrammed computer operation as previously generally considered.

With respect to maintenance operations, the computer 304 is programmedto count the number of normal and emergency starts and to accumulate thenumber of hours at various levels of load operation. Maintenenceprocedures are speeded by the availability of the five hold points inthe starting sequence considered previously in connection with theoperator's panel 120 and the availability of manual procedures foroperating the voltage regulator and for synchronizing from theoperator's panel 120. The ability to display thermocouple temperatures,vibration levels, and various other variables and the ability to changelimits through use of the operator's console package also providesmaintenance convenience.

Shutdown of the gas turbine is caused if any of three time checks failduring the startup sequence. The first time check which measures timefrom initiation of the master contactor function to ignition speed hasalready been considered. In addition, a check is made on the time fromdetection of flame in both combustor baskets to 60% speed. Further, acheck is made on the time from starting engine trip at 60% rated speedto idle speed.

If a normal shutdown is requested locally or remotely the load is firstcut back at a predetermined rate until minimum load is reached and thegenerator main and field breakers and the fuel valves are then tripped.In an emergency shutdown, the generator main and field breakers and thefuel valves are tripped immediately without reducing the load to theminimum level. All trouble shutdowns are classified as emergencyshutdowns.

The gas turbine 104 coasts down during shutdown and as the oil pressurefrom the shaft driven pump drops the DC auxiliary lubrication oil pumpis energized. At about 15% rated speed, or at a higher speed such as 50%rated, the turning gear speed equal to about 5 RPM, a turning gearoverrunning clutch engages to allow the turning gear motor to rotate theturbine at the turning gear speed. After the cooling period of up to 60hours, the turning gear and the auxiliary lubrication oil pump arestopped and the shutdown sequence is completed.

d. Sequence Logic Charts

In FIGS. 33A through 33F, there are shown logic diagrams representingthe various alarm and sequencing functions performed by the sequencingprogram 600 in the block 626 (FIG. 31) each time it is executed.Predetermined logic building blocks are employed in defining theconditions for the performance of the sequencing program functions. Eachblock contains a symbol identifying its function and a number ofalphanumeric character providing a program block identification. Thelogic function identifying symbol is generally located above the programblock identification character. The following is a list of the logicsymbols and the logic functions to which they correspond:

    ______________________________________                                        A             And                                                             OR            OR                                                              FL            Flip Flop                                                       SS            SINGLE SHOT                                                     DB            DEAD BAND                                                       NOT           INVERSION                                                       TDH           TIME DELAY - HOURS                                              TDS           TIME DELAY - SECONDS                                            ______________________________________                                    

With respect to flip-flops FL, the letter S signifies a set input andthe letter C signifies a clear input. On the rightmost side of eachflip-flop block, the numerals 1 and 0 indicate outputs and the 1 outputis assumed to have a logic state of 1 when the flip-flop is set and the0 output is assumed to have a logic state of 1 when the flip-flop iscleared.

In Fig. 33A, there is principally shown the logic associated withstart/stop operations and the master contactor or control function towhich reference has already been made. Generally, logic diagram 642pertains to the master contactor or control function generated byflip-flop FL7 as a function of pushbutton operations and otherconditions. Similarly, logic diagram 644 relates to the generation of ashutdown operation in response to pushbutton, shutdown alarm and otherconditions. Thus, shutdown OR block OR6 resets the master contactfunction flip-flop FL7 when a shutdown is initiated. In the logicdiagram 644, alarm shutdowns are initiated by line L86 through block OR4as derived from the lower left area of FIG. 33D. On shutdown, singleshot block 6 provides for registering predetermined data. Shutdownoperation of the starting engine is set forth in FIG. 33B.

Other sequencing program logic functions set forth in logic diagram formin FIG. 33A include a plurality of generator alarms designated as OR GENBLK blocks. In addition, block OR1 provides for immediate shutdown onblade path over-temperature through block OR4. Single shot blocks 4, 5and 14 respectively provide normal start counts, emergency start counts,and abort counts. A list of miscellaneous alarms is also included.

In FIG. 33 B, there are shown principally the logic diagrams associatedwith the turbine sequencing functions from the point in time at whichthe master contact function is initiated up to ignition. In logicdiagram 646, flip-flop FL9 registers the master contactor function fromline L4 to energize the auxiliary lubrication oil pump line starter. Theturbine turning gear starter is then energized by a block A9 if no HOLDis present. The logic block A9 also causes the turning gear motor to beturned off at the selected speed such as 15% rated as in FIG. 18 or at50% rated as in the application described herein. If the lubricationpressure does not build up within 30 seconds, the turbine shuts down.FL9 is cleared after a minimum of 60 hours cooloff to control turninggear cooloff operation.

Block OR14 provides for instrument air valve solenoid energization inresponse to the master contactor function L4. On shutdown, theinstrument air is left on until coastdown to about 10% rated where 63-6is reset. Block A10 causes diesel startup once the block inputconditions are satisfied including the master contactor function L4,turning gear energization and adequate lubrication oil pressure.Overspeed trip valve solenoid operation and gas valve solenoid operationare initiated by block A11 when the gas turbine 104 has reached firingspeed and when purge time has expired.

Once the input logic conditions are satisfied for block A17, theignition relay is caused to be energized by block A20 and a time delayfunction is initiated by block TD19. When fuel oil is selected, blockA20 provides for appropriately timed introduction of atomizing air intothe combustor baskets. Other functions performed in firing logic diagram648 include flame detector logic processing for alarms as provided byblocks A21 through A24. The logic for combustor basket purging andmultiple ignition attempts and turbine shutdown following ignitionfailure is also included in logic diagram 648.

Other logic functions included in FIG. 33B are the time of ignitionspeed check provided by AND block A13 and the time check for flameverification to 60% speed provided by block A68A. The conditions whichdefine starting motor trip are processed by block OR38 and dieselshutdown is initiated by block OR10 at 60% rated speed. Operation of thecompressor bleed valve solenoids, the evaporative cooler, thecirculating oil pump, and the lubrication oil cooler fan are provided asindicated by the associated logic blocks.

The sequencing logic associated with Mode 2 operation, i.e.synchronizing, is principally set forth in FIG. 33C. Under the indicatedlogic conditions, block OR41 in logic diagram 650 provides for fieldbreaker closure. Manual field breaker operation is provided throughblock AOC while automatic operation is provided through block A41.Automatic and manual field breaker trip is provided through blocks OR42,A42 and SS42.

In logic diagram 652, block OR45 verifies bleed valve closure. If blockFLOC indicates a manual sync selection, block AOC provides for generatorbreaker closure when block FLOC receives a set pulse from the GEN SYNCpushbutton if the GEN BKR CLOSE pushbutton is depressed. Automaticgenerator breaker closure is provided by block A45 after the automaticsynchronization program 608 in response to a request made by block A45when the appropriate conditions for synchronization are established.Generator breaker trip is provided by block SS47 and by the indicatedbearing condition.

Automatic closing of the generator onto a dead bus is provided outsideof the automatic synchronizing program. Further, programminginterlocking is provided to make sure no more than one generator breakerwill attempt to close onto the dead bus simultaneously by the added,unnumbered OR, NOT and TD blocks. Generator voltage must have built upabove 13 KV.

Generator voltage control is provided by logic diagram 654 in accordancewith operator selections detected by block FL1. The panel RAISE andLOWER pushbuttons cause base rheostat adjustment through the two topmostblocks A1 and voltage adjust rheostat operation through the twolowermost blocks A1. As already considered, voltage adjust rheostatposition defines a voltage setpoint to which the local control circuitryresulates the generator voltage. Line breaker functioning is provided asindicated by logic diagram 656. Block A44 provides a time check foroperation from starting engine trip to idle speed. Disc cavitytemperature alarms are generated by blocks OR80 and A80. Anotherfunction includes in FIG. 33C is low limit action provided on the fueldemand signal by block FF91.

The logic processing of local and remote shutdown conditions is shown inlogic diagram 658 in FIG. 33D. Blocks OR66 and OR68 cause shutdownthrough block FF68A and line L86 considered previously in connectionwith FIG. 33A. The various alarm conditions which result in shutdown aresubsequently set forth in connection with consideration of the alarmprogram 610.

It is noteworthy that a multiple shot provision is provided forshutdown. Instead of the usual shutdown and lockout procedure whichrequires an attendant on the site for restart, a selection can be madeby the plant owner as to when lockout will occur. Thus, a number ofnonlockout shutdowns is specified for a selected time interval andlockout only occurs when the actual number of shutdowns in the selectedtime interval exceeds the selected shutdown number by one. For example,lockout may be set if more than one shutdown occurs within a one hourtime period.

Other logic features included in FIG. 33D include block OR73-77 whichinhibits start under the indicated logic conditions and the variousblocks A and OR which generate vibration alarms. Further, remoteshutdown and lockout is generated by block FL71. Miscellaneous alarmsare provided by blocks A69, A68, A PATCH, and OR PATCH.

In FIG. 33E, logic diagram 660 provides the logic which processes thefuel selection pushbutton settings in determining the fuel control to beoperated in the external circuitry at block FL81. Logic diagram 652relates to a fuel transfer ramp generator which is considered more fullyin the previously mentioned copending Reuther patent application.Finally, logic diagram 664 pertains to AC-DC fuel transfer pump control.

The logic associated with control program mode selection for interfacewith the control program 602 is set forth in logic diagram 666 in FIG.33F. Block OR91 and the four blocks FL91 provide the output indicationsof the control mode. In logic diagram 668, a five state flip-flop FLresponds to the indicated logic blocks to detect the pushbutton loadselection. The outputs of the block FL are employed in the controlprogram mode selection logic diagram 666 and in the control program 602.The logic employed for incrementing and decrementing the kilowattreference from the operator's panel 120 is included in the controlprogram 602.

In logic diagram 670, there are provided the logic blocks needed forresponding to the various sequence pushbuttons and the HOLD pushbuttonto determine when each of the five hold logic blocks FLOC should be setto signal a call for the associated hold. Logic diagram 670 alsoprovides for holding the speed reference during acceleration. HOLD 5 isselected to avoid time out on sequence times. In addition, blocks A89and OR89 provide for the previously described pushbutton flashconditions. The sequential illumination process on the panel 120 duringstartup logically and conveniently provides a display of startupinformation to the plant operator.

e. Macro Instructions For Sequencing Logic And Logic Subroutines AndRelated Macros

In order to improve the efficiency with which desired functions areimplemented in machine language instuctions for process control, a groupof Macro instructions are employed to provide direct programming ofrepetitive and interacting elemental function blocks for assembly intomachine language. The Macro instructions accordingly provide a compilertype function in the programming process for control systemapplications. In this case, a set of Macros are constructed to providefor direct programming of logic blocks in a logic system. The LogicMacros generally facilitate process control programming and areparticularly advantageous in gas turbine power plant applicationsbecause of the volume of sequencing logic involved therein and,accordingly, because of the large amount of programming effort that canbe avoided with use of the Logic Macros.

Generally, an assembly or higher level program for a particular computeroperates in response to an input statement to generate a machinelanguage form of the input statement. The assembly program ischaracterized with a set of instructions, and these instructions areused as language elements in making the input statement.

In the present use, the stand P50 assembly program has a macroinstruction capability, i.e it is internally structured to accept macrosinitially defined by assembly language elements. Entry of the LogicMacros into the assembly program enables it to respond to a coding forthe Logic Macros during assembly of another program which has beenwritten with use of the Logic Macros along with the assembly languageelements. Accordingly, with the use of a Logic Macro, the assemblyprogram is made to respond to the Macro mnemonic and other related keydata elements whch follow the mnemonic to generate an entire set ofmachine language instructions which would otherwise have to beindividually entered into the assembly program as individual statements.In use of the assembled program, the Macro generated set of instructionsthen operates to perform the specified logic function. It is alsonoteworthy that certain Macros are structured so that the assemblyprogram generates only the necessary machine language statements forprocessing particular input conditions specified for the Macro asopposed to generating the entire set of possible machine languageinstructions needed to embrace all of the possible input conditions.

The Logic Macros are made small enough for efficient use in "in line" or"on line" program execution, i.e. for repeated use as opposed to a jumpto a single external subroutine. Further, they can be interspersed withassembly language statements or used alone in sequential combinations inthe process of writing a program in assembly language. In use, thevarious Logic Macros represent logic functions for which various inputlogic conditions can be specified. Each Macro causes the assemblyprogram to generate a set of instructions which operate on the specifiedMacro input conditions to generate a machine language instruction blockwhich will execute the logic functions defined by the Macro for thespecified input conditions. Similar types of results are achieved withthe use of Control Macros also employed in the preferred embodiment andset forth in a subsequent section herein.

The Logic and Control Macro details are herein based on the assemblylanguage available for the P50 computer. Other computer applications ofthe Macros involve the use of other languages associated with thoseapplications.

Logic subroutines employed in the program system and other Macrosrelated to those subroutines are also considered under this heading.

    __________________________________________________________________________    TIMING:                                                                       1. MACROS                                                                     1. AL1 Load Accumulator                                                               ##STR19##                                                                    FORM: AL1 FROM, INDIR                                                         NOTE: (a) Load FROM in AL                                              2. AS1 Store Accumulator                                                              ##STR20##                                                                    FORM: AS1 WHERE, INDIR                                                        NOTE: Store AL at WHERE                                                3. XFR Transfer Value of One Variable to Another                                      ##STR21##                                                                    FORM: SFR FROM, TO                                                            NOTE: a. Transfer FROM to TO                                                  b. AL is not a valid argument                                          4. ORR Logical Inclusive - Or                                                         ##STR22##                                                                    FORM: ORR N, I1, I2, I3, . . ., IN                                            a. N = 1, 2, 3, 4, . . ., 10 inputs                                           b. I = an input varible (AL is valid input argument if and only               if                                                                            placed in I1 position in macro heading)                                       NOTE: a. Exit with output in AL                                        5. ANN Logical AND Function                                                           ##STR23##                                                                    FORM: ANN, N, I1, I2, I3, . . ., IN                                           a. N = 1, 2, 3, 4, . . ., 10 inputs                                           b. I = an input variable (AL is valid input argument only if                  placed                                                                        in the I1 position in the macro heading)                                      NOTE: a. Exit with output in AL                                        6. MAK Set the State of a Logical Variable                                            ##STR24##                                                                    (True or False)                                                               FORM: MAK VAR, COND                                                           a. VAR = Logical variable                                                     b. COND = condition TRUE or FALSE                                             NOTE: a. The TRUE condition sets the most significant bit of VAR              equal                                                                         to 1 (negative number). The FALSE condition sets the most                     significant bit of VAR equal to 0 (positive number).                   7. IFF Test the State of a Logical Variable                                           ##STR25##                                                                    FORM: IFF VAR, COND, LABEL                                                    a. VAR = logical variable (AL is valid)                                       b. COND = condition TRUE or FALSE                                             c. LABEL = some unique mnemonic                                        8. NOT Logical Complement                                                             ##STR26##                                                                    FORM: NOT INPUT                                                               a. INPUT = input variable (AL is valid)                                       NOTE: a. Exit with output in AL                                        9. ALM Alarm Macro                                                                   FORM: ALM ALMBIT                                                              a. ALMBIT = Alarm bit number of alarm to be set                               NOTE: a. Each alarm has been assigned an alarm bit number (1, 2,              3, 4,                                                                         . . ., 84). Capable of handling up to and including 84 alarms                 since                                                                         six 14-bit words have been alloted for the alarm table.                        ##STR27##                                                                     ##STR28##                                                             10. FFP                                                                              Flip - Flop                                                                    ##STR29##                                                                    FORM: FFP SET, RESET, OUTPUT                                                  a. SET = set variable (AL is valid)                                           b. RESET = clear variable (AL not valid)                                      c. OUTPUT = a logical variable which must be in the turbine                   resident                                                                      table (AL not valid)                                                          NOTE: a. The OUTPUT remains in the TRUE state until the RESET                 vari-                                                                         abel becomes TRUE. If both inputs are TRUE, the RESET vari-                   able takes precedence over the SET variable.                           11. INC                                                                              Increment Specified Variable                                                   ##STR30##                                                                    FORM: INC VAR                                                                 a. VAR = Specified variable                                                   NOTE: a. Add 1 to the specified variable VAR and store results in             VAR.                                                                   12. DBD                                                                              Dead Band                                                                      ##STR31##                                                                    FORM: DBD INPUT, ON, OFF, OUTPUT                                              a. INPUT, ON, and OFF arguments must refer to analog type                     quantities                                                                    b. OUTPUT argument is a logical variable which must be in the                 turbine resident table (AL not valid)                                         NOTE: a. if INPUT > ON, OUTPUT = TRUE                                         if INPUT < OFF, OUTPUT = FALSE                                                if OFF < INPUT < ON, OUTPUT = LAST VALUE                               13. JPT                                                                              Jump Macro                                                                    FORM: JPT LABEL                                                               a. LABEL = some unique mnemonic                                               NOTE: a. unconditional jump to LABEL                                   14. SSF                                                                              Single - Shot Function                                                         ##STR32##                                                                    FORM: SSF N, INPUT, OUTPUT                                                    a. N = number assigned to the particular single shot.                         b. INPUT = input variable (AL valid)                                          c. OUTPUT = a logical variable which must be in the turbine                   resident                                                                       table (AL not valid)                                                         NOTE: a. OUTPUT = TRUE only for the first period where the input              is TRUE                                                                        ##STR33##                                                                     ##STR34##                                                             15. TDS                                                                              Second Time Delay Macro                                                        ##STR35##                                                                    FORM: TDS NUMBER, INPUT                                                       a. NUMBER = number of the time delay - each second time delay                 has been assigned a number beginning with 0.                                  b. INPUT = variable (AL valid)                                                NOTE: a. If INPUT is TRUE for "ORGCNT" consecutive periods AL set             TRUE. If at any time INPUT goes FALSE, OUTPUT is set                          FALSE and "ACTCNT" is reset to "ORGCNT"                                       b. Exit with output in AL                                              16. SUM                                                                              Add Specified Increment to Variable                                            ##STR36##                                                                    FORM: SUM VAR, INCR                                                           a. VAR = variable                                                             b. INCR = specified increment                                                 NOTE: a. Add specified increment to the variable and store the                results in                                                                    the variable location.                                                 17. TDH                                                                              Hour Time Delay Macro                                                          ##STR37##                                                                    FORM: TDH NUMBER, INPUT                                                       a. NUMBER = number of the time delay - each hour delay has been               assigned a number beginning with 0.                                           b. INPUT = input variable (AL valid)                                          NOTE: a. If INPUT is TRUE for "ORGKNT" periods, AL set TRUE. If               at any time INPUT goes false output is set FALSE, "DECSEC"                    is reset and "ACTKNT" is reset to "ORGKNT" valve.                             b. Exit with output in AL                                              18. CPS                                                                              Compare and Set Macro                                                          ##STR38##                                                                    FORM: CPS A, B                                                                a. A and B are input variables                                                NOTE: a. If A ≧ B; AL set TRUE                                         If A ≦ B; AL set FALSE                                                 b. Exit with output in AL                                              19. NRR                                                                              Special Macro that "NOT"s Inputs Before "OR"ing                                ##STR39##                                                                    FORM: NRR N, I1, I2, . . ., IN                                                a. N = number of inputs - maximum capability is five inputs.                  b. I1, I2, . . ., IN = input variables (AL valid if and only if               used in I1                                                                    position in macro heading)                                                    NOTE: a. Take regular inputs (5 maximum, "NOT" them, and then "OR"            them                                                                          b. Exit with OUTPUT in AL                                              20. CPR                                                                              Compare Macro                                                                  ##STR40##                                                                    FORM: CPR INPUT, WITH, HIGHER, LOWER, EQUAL                                   a. INPUT = input variable                                                     b. WITH = specified value                                                     c. HIGHER, LOWER, EQUAL = logic outputs                                       NOTE: a. INPUT > WITH: HIGHER = TRUE; LOWER = EQUAL = FALSE                   INPUT = WITH: EQUAL = TRUE; HIGHER = LOWER = FALSE                            INPUT < WITH: LOWER = TRUE; HIGHER = EQUAL = FALSE                     1. PAK Pack Macro                                                                    FORM: PAK WORD, TABLE                                                         a. WORD = word in resident table where packed word is stored.                 (AL valid)                                                                    b. TABLE = beginning address in sequencing data area where packing            begins.                                                                2. UPK Unpack Macro                                                                  FORM: UPK WORD, TABLE                                                         a. WORD = word to be unpacked (Al valid)                                      b. TABLE = address where bit 0 of the word being unpacked will                be stored. Bit 13 is placed in location "TABLE + 13"                   3. HCT Hour Count Macro                                                              FORM: HCT HOUR                                                                a. HOUR =  beginning address of elapsed hours table (depending                upon operation mode) in the sequencing data area.                      4. RSF Right Shift Macro                                                             FORM: RSF N                                                                   a. N = number of times the word in question is to be shifted (N               ≦ 13)                                                           5. SBT Store Bit Macro                                                               FORM: SBT N                                                                   a. BIT N of Operator's Console BIT Table (BITTBL) to the value                of the sign BIT in the Accumulator. The Accumulator sign BIT                  is left undisturbed.                                                   __________________________________________________________________________

II. LOGIC SUBROUTINES AND RELATED MACROS

1. Left Shift Subroutine (LSHSB)

With a single call to the left shift subroutine, a 14 bit word can beleft shifted a maximum of thirteen times.

Since no macro has been defined to work in conjunction with thissubroutine, the word to be shifted and the number of shifts (N≦13) mustbe loaded in the accumulator and designator register respectively uponentry to this subroutine.

By incorporating the P-50 left shift instruction (LSH) and a loop toform the framework of this routine, time has been utilized moreefficiently in comparison with using the P-50 left shift instructionsolely. The above statement is especially true when it is necessary toleft shift a word several times, remembering that one P-50 left shiftinstruction left shifts the operand to the left one bit position only.

2. Right Shift Subroutine (RSHSB) and Right Shift Macro (RSF)

The right shift subroutine differs from the left shift subroutine inonly one respect.

The right shift routine works in conjunction with the right shift macro(RSF) whose only argument is the number of times the specified word isto be right shifted (N≦13). The prototype instruction of the RSF macroload the number of right shifts in the designator register beforecalling the right shift subroutine.

In all other respects this routine and the left shift subroutine areidentical.

3. Accumulate Elapsed Hours Subroutine (ACMSUB) and Hour Count Macro(HCT)

Working with the hour count macro (HCT), the accumulate hours subroutinekeeps track of the number of hours that have elapsed in the variousoperation modes (minimum, base, peak, and system reserve).

A record of elapsed hours is kept by the first reserving two locations(see table below) for each of the operation modes in the whole word(read/write) portion of the sequencing data area. The first of these twolocations houses the number of elapsed hours that have accumulated inthe particular operation mode (location initially set to zero). Thesecond location contains the second count (initially set to 3600₁₀(number of seconds/hour)). The second count is a function of the runperiod.

Each time the program runs the second count (location two) isdecremented until it reaches a negative zero, remembering that when aone is decremented, a negative zero results. At this time the hour count(location one) is incremented and the second count is reset to 3600₁₀.Thus, at this point in time (using the above as an example), one hourhas accumulated in this particular operation mode.

Upon entry into the ACMSUB subroutine the last address in the elapsedhour table (both the address and the table depending upon the mode ofoperation) must be loaded in the accumulator. The HCT macro sets up thisaddress in the accumulator before calling the ACMSUB subroutine.

    __________________________________________________________________________    ELAPSED HOUR TABLES                                                           __________________________________________________________________________     ##STR41##                                                                     ##STR42##                                                                     ##STR43##                                                                     ##STR44##                                                                    __________________________________________________________________________

4. Compare Subroutine (CPRSB) and Compare Macro (CPR)

In the macro prototype instructions, a specified value is subtractedfrom the input, both of which are identified as arguments in the macroheading. The resulting difference (>0,<0, or=0) is loaded in theaccumulator before the compare routine is called. The three locationsfollowing the subroutine call instruction in the compare macro containthe address of the output variable to be set on the higher condition(difference>0), the address of the variable to be set on the lowercondition (difference<0), and the address of the variable to be set onthe equal condition (difference=0) respectively.

Upon entry, the compare subroutine expects the accumulator to be loadedwith the difference mentioned above and the location of the outputs tobe readily available.

The subroutine compares the difference with the outputs and sets orclears the most significant bits of the outputs to indicate thecondition. If the difference=0, the most significant bit of the equalvariable is set and the most significant bits of the remaining twooutput variable are cleared. If the difference<0, the most significantbit of the lower variable is set, and the most significant bits of theremaining two variables are cleared. If the difference>0, the mostsignificant bit of the higher variable is set, and the most significantbits of the remaining two output variables are cleared.

The CPR instruction is used extensively in the ramp generation of thesequencing logic.

5. Second Time Delay Subroutine (TDLSEK) and Second Macro (TDS)

Since there are several second time delays in the sequencing logic whichmust be taken into consideration, the second time delay subroutine andmacro have been defined.

The two arguments in the TDS macro heading are the number of the timedelay and the input into this time delay. The prototype instructions ofthe TDS macro enter the input into the accumulator. The number of thetime delay along with the beginning location of the second delay tablesin the sequencing data area (SECTBL) are used to determine the lastaddress of the second table for the particular delay being considered.This address is located immediately following the subroutine callinstruction in the TDS MACRO.

Once the subroutine has been entered, the input must remain set for"ORGCNT" consecutive seconds before the output is set. That is, thecontents of the second delay count location in the tables must bedecremented to zero with the input set continuously. If at any time theinput goes false, the delay count is started anew and the output is setfalse.

The second time delay tables configuration is as follows:

    __________________________________________________________________________    SECOND TABLES                                                                 __________________________________________________________________________     ##STR45##                                                                     ##STR46##                                                                    __________________________________________________________________________

a. Each second time delay is numbered beginning with #0.

b. The beginning address of the second tables is SECTBL.

c. Each second time delay occupies two locations in the second timedelay tables which lie in the whole word portion of the sequencing dataarea.

(1) Location one of each table: contains the actual count (ACTCNT) to toin seconds. Initially this is the amount of the delay in seconds. Thislocation is counted down each time the program runs. The contents ofthis location is a function of the run period (RUNPER).

(2) Location two of each table: contains the original count (ORGCNT) inseconds. Initialized as the amount of the delay and never changes. Thislocation is used to reset location one if the input should go false atany time.

6. Unpack Subroutine (UNPAK) and Unpack Macro (UPK)

The unpack macro and unpack subroutine work together to unpack the 14bits of a word into the most significant bits of the words in a packedword table located in the sequencing data area.

The arguments in the unpack macro heading identify the word to beunpacked and the beginning address of the table in the sequencing dataarea where this word is to be unpacked. The last address in the tablewhere this word is to be unpacked is located following the RJPinstruction in the UPK macro. This last address is simply the beginningaddress +13.

Once all this necessary information is set up, the unpack subroutineunpacks the word as follows: Bit 1 of the word goes to the first addressof the table, Bits 2,3, . . . , 14 go into increasing core locations.Thus Bit 14 is stored in the last address of this table in thesequencing data area.

See the logic pre-processor write-up for further explanation of themethod used in unpacking.

7. Pack Subroutine (PAK) and Pack Macro (PAK)

PAK and PAK are teamed together to accomplish the opposite of the unpacksubroutine and macro. The format of the PAK macro is the same as the UPKmacro.

First the pack macro sets up the beginning address of the packed wordsection of the sequencing data area where the packing is to begin.

The subroutine then packs the most significant bits of fourteen words(beginning with the word located at the address set up by the PAK macroand progressing sequentially from this beginning address). Thesefourteen most significant bits are packed into a single fourteen bitword. The first address in the turbine resident table where the firstpacked word is stored can be found following the subroutine callinstruction in the PAK macro.

The above mentioned packing process is continued until all of the packedword section of the sequencing data area has been packed and stored inthe turbine resident table.

8. Hour Time Delay Subroutine (TDLHRS) and Hour Macro (TDH)

The TDLHRS subroutine and TDH macro were originated to handle the hourtime delays which were present in the sequencing logic. The format ofthe hour macro is the same as the second macro.

Before proceeding to the hour delay subroutine, the input must be loadedin the accumulator and the last address in the delay table of the hourdelay being considered must be available. The TDH macro accomplishes theabove. The last address in the delay table is found following the RJPinstruction in the TDH macro.

Once the subroutine is entered the input must be set for "ORGKNT"consecutive hours before the output is set. If at any time the inputgoes false, the output is set false and the delay count isre-initialized.

The hour time delay tables configuration is as follows:

    __________________________________________________________________________    HOUR TABLES                                                                   __________________________________________________________________________     ##STR47##                                                                     ##STR48##                                                                    __________________________________________________________________________

a. Each hour time delay is numbered beginning with #0.

b. The beginning address of the hour tables is HRTBL.

c. Each hour time delay occupies three locations in the hour time delaytables which lie in the whole word portion of the sequencing data area.

(1) Location one of each table: contains the second count (DECSEC)Initially this location contains the following:

    3600* 4/RUNPER

where RUNPER (run period) is specified in multiples of 1/4 of a second.Therefore: 1/4 * RUNPER=time (in seconds) it takes for the program torun. If the program runs once a second for example,

    1/4*RUNPER=1Sec.

    RUNPER=4

Therefore, in this example, location one of the table equals initially:

    3600*4/RUNPER=

    3600*4/4=3600

After location one has been decremented 3600 times (one hour elapsed),location two (actual count to go in hours) is decremented provided theinput has remained set throughout this period. If delay time has notexpired location two is reset to its initial value.

(2) Location two of each table: contains the actual count (ACTKNT) to goin hours. This location initially contains the amount of the hour delayminus one and is counted down each time location one has beendecremented to negative zero.

(3) Location three of each table: contains the original count (ORGKNT)in hours. This location always contains the total amount of theparticular delay in hours minus one. If the input goes false at any timethe contents of the location is used to reset the contents of locationtwo.

9. Alarm Set and Find Bit Subroutines (ALMST & FNDBT) and Alarm Macro(ALM)

In order to set the correct alarm once an alarm condition has beenencountered, two subroutines (ALMST & FNDBT) which work in conjunctionwith the alarm macro (ALM) have been employed.

The alarm number (ALMBIT=1,2,3, . . . , or 84) of the alarm to be set isthe only argument in the ALM macro heading. This alarm number is loadedin the accumulator before entering ALMST.

Immediately after entering ALMST, advance to FNDBT to determine the wordnumber (WRDNUM=0,1, . . . , or 5) and the bit number (BITNUM=0,1,2, . .. , or 13) which correspond to this particular alarm number. Both ofthese values are stored before returning to ALMST.

Once back in ALMST, the address in the alarm section of the sequencingdata area where this alarm bit lies must be pinpointed. Adding the wordmnumber (WRDNUM) found in FNDBT to the beginning address (ALMTBL) of thealarm section of the sequencing data area accomplishes this task. Nowset the alarm bit in this word which corresponds to the original alarmnumber.

10. Compare & Set Subroutine (CPSSB) and Compare and Set Macro (CPS)

In order to compare two inputs and set the output either TRUE or FALSEaccording to the relative values of the inputs, CPSSB and CPS have beendefined.

The compare and set macro identifies the two inputs to be compared inthe arguments of the macro heading. The prototype instruction of CPSsubtracts the second input identified from the first input identifiedleaving the results (positive or negative) in the accumulator beforecalling CPSSB.

Entering CPSSB with the difference in the accumulator, the output is setTRUE or FALSE depending upon whether the difference is positive ornegative respectively.

11. Inclusive-or Subroutine (IORSB) and Macro (ORR)

Since the P-50 repertoire of instructions does not include aninclusive-or instruction, IORSB and its calling macro (ORR) have beendefined. The inclusive-or macro has the capability of handling up to teninputs to the IOR gate.

The arguments of ORR include the number of inputs (N≦10) to the IOR gateand the inputs. The addresses of the inputs are located following thedelete instruction in the inclusive-or macro in the reverse order oftheir identification in the macro heading. Thus, the address of the lastinput identified in the macro heading is in the location immediatelyfollowing the delete instruction.

Before proceeding to the inclusive-or routine, the value of the firstinput is loaded in the accumulator.

In IORSB, the first inputs is "inclusive-or"ed with the last input. Theresults of the first "or" is then "inclusive-or"ed with the next to lastinput and so on, until all the inputs have been "or"ed. This aboveprocess is terminated when a zero is encountered in the table of inputswhich follows the call to the "or"ing subroutine in the "ORR" macro.

12. Function Generator and Interpolation Routines (2DIMN, 1DIMN, INTERP)##STR49##

In a two dimensional case, the function will be specified in thefollowing form: ##STR50##

A maximum of five segments will be given and breakpoints may occuranywhere.

For a given input variable x, f(x) can be determined for both themaximum cruve and the minimum curve.

First consider the minimum curve. Knowing the input variable x and thelocation of the table of breakpoints for the minimum curve (see tablebelow), the following function can be utilized to approximate thefunction y(minimum)=f(x): ##EQU3## where:

a. x is the given input variable

b. y is the f(x) corresponding to the given input variable x

c. x(n)≦x≦x (n+1) and y(n)≦y≦y (n+1)

d. ΔX=x(n+1)-x(n).

1DIMN is the one dimensional function generator routine which is used toset up the necessary information for interpolation. Once all thisinformation is set up, INTERP is entered. INTERP is the routine whichexecutes the actual interpolation.

Once the f(x) for the minimum curve has been calculated and stored forlater use, calculate f(x) for the maximum curve using the sameprocedure.

In the two dimension case, Z=f(x,y) must be approximated. Severalquantities must be made available in order to accomplish thisapproximation. 2DIMN is the two dimensional function generator routinewhich sets up these quantities in a manner that INTERP can again be usedfor interpolation. The quantities necessary for the approximation off(x,y) are as follows:

a. x & y - given input variables

b. y(maximum)-location on the y-axis of the y=y (maximum) curve

c. y (minimum)-location on the y-axis of the y=y (minimum) curve

d. f(x) minimum=[f(x) calculated for minimum curve in firstinterpolation]

e. f(x) maximum - [f(x) calculated for maximum curve in the secondinterpolation]

The function used to approximate f(x,y) is as follows: ##EQU4##

These routines have been designed to be as efficient, versatile, andgeneral as possible.

Each function has a two dimensional function generator table connectedwith it. The configuration of this table is as follows:

y(minimum)

y(maximum)

NUMPTS values of x for curve A

NUMPTS values of f (x,y (minimum))

NUMPTS values of x for curve B

NUMPTS values of f (x,y(maximum))

a. NUMPTS=the number of breakpoints/curve.

b. 4* NUMPTS+2= length of each table.

8. Control Program

The control program 602 interacts with the sequencing program 600generally to provide for control loop determination of the operation ofthe gas turbine power plant 100, and like plants if provided, inaccordance with the control arrangement considered in connection withFIG. 34. As just considered, the sequencing program 600 is organized toprovide efficient and reliable interfacing with the plant and theoperator panel in determining the control mode in which the controlprogram 602 is to be operated. Control mode directives are madecompatible with protective turbine performance and orderly managementover advances in the gas turbine operational process. The control system300 is in this embodiment provided with a control loop arrangement 300Ain which the hybrid interface is preferably made as shown to provide forsoftware speed reference generation and software selection of a singlelow fuel demand limit in a software low select block 700 for applicationto the analog hardware speed control 324.

The output fuel demand signal is selected as the lowest of a speed errorfuel demand signal and the computer output fuel demand limit signal aspreviously considered. The actual fuel demand control signal ACTFL isread as an analog input for tracking in various software control pathsas considered more fully subsequently. Surge limit, blade path andexhaust temperature limit and load limit control loops are all providedwith software control functions which respond to external data andgenerate outputs to the software low select block 700 as indicated bythe respective reference characters 702, 704, 706 and 708.

Data flow for the control program 602 is similar to that consideredpreviously in connection with the sequencing program 600. Thus, thecontrol program 602 first provides for preprocessing of analog inputdata and other data in block 710 for use in block 712 where the gasturbine control functions are performed.

In the first execution of the control program 602, the preprocessorblock 710 acquires a resident control data table for turbine A therebyacquiring all the required values which represent the current status ofturbine A. For example, the resident table stores such values as theprevious inputs and outputs for the reset functions and rate functions.Other tabled values include function generator tables for all functionsalong with control function gains.

The resident control data table also includes the address of the turbinesequencing resident table which enables the preprocessor 710 to accessthe sequencing table and determine the control mode of operation, theselected load and emergency or normal startup status. After acquisitionof the sequencing data for the turbine A, an analog data acquisition isemployed to obtain the analog data needed for control program execution.The analog data required includes the eight blade path temperatures, theeight exhaust temperatures, compressor inlet temperature, combustorshell pressure, actual fuel signal demand and actual kilowatt output.Critical analog inputs such as compressor inlet temperature andcombustor shell pressure are preferably given special reliability checksby sequencing logic in FIG. 33.

Preprocessing of the blade path and exhaust path temperaturerepresentations to find the respective high averages in the mannerpreviously considered in connection with FIG. 15 is performed by thepreprocessor block 710 as somewhat detailed in FIGS. 42 and 43 after theanalog data is acquired. It is noted in further detail that the controlprogram processing of the blade and exhaust temperature representationsincludes checking each thermocouple for open circuits. If a largenegative test voltage value is detected for a thermocouple, the outputof that thermocouple is discarded in calculating the average temperatureindication. After the temperature average is calculated, eachthermocouple output is compared to the average for its group and if itis lower than the average by more than a predetermined amount, the lowthermocouple values are discarded and the average blade and/or exhausttemperature is recomputed. The described computational cycle is repeateduntil no low values are determined or until no values area left fordiscard in which case an alarm is generated. Data processing for theimportant blade and exhaust process thermocouples in this mannerprovides reliable plant protection against overheating and foreshortenedturbine life.

Next, the turbine control block 712 is executed and it makes use of theacquired data including the sequencing, analog and resident control datawhich is stored in a table indicated by the block 714. After completionof the execution of the turbine control block 712, a postprocessor block714 is executed to transfer an updated resident control table forturbine A back to its resident core area. The program process justconsidered is then repeated for turbines B, C and D according to thenumber of gas turbine plants placed under control. After the lastturbine has been serviced with control program execution, an exit ismade from the control program postprocessor block 714.

In FIG. 37, the control block 712 is shown in greater detail. Adetermination is first made from the turbine sequencing table by block718 whether the turbine under control is in Mode 0 status. If so, block720 is executed, but no control action is taken since Mode 0 is aninitialization mode. Thus, block 720 zeroes the previous value locationsfor the blde path and exhaust temperature control and resets errorflags. Block 720 also provides for tracking the actual turbine speed sothat a smooth transition is made in the computer generated speedreference during transfer from Mode 0 to Mode 1.

If the control is not in Mode 0, block 722 next determines the surgecontrol function for use in the surge limit control loop (FIG. 34) inall other modes of operation. To prevent compressor surge underexcessive pumping demand, the surge control function determines amaximum fuel demand limit as a function of the compressor inlettemperature and the combustor shell pressure (compressor outletpressure) which are obtained from reliability checked analog inputs.

As previously considered generally in connection with FIG. 15, the surgelimit functional determination is made with the employment of storednonlinear curve data which is representative of the nonlinear turbinesurge operating limit over startup and load operating ranges. In thisinstance, the pair of nonlinear curves 326 and 328 are stored forrespective compressor inlet temperatures of 120° F. and -40° F. Thecurves 326 and 328 are stored by the use of five points on each curveand intermediate curve points are determined by a linear interpolationroutine considered previously in connection with the sequencing LogicMacro instructions. Curve points for compressor inlet temperaturesbetween -40° F. and 120° F. are determined by a second linearinterpolation procedure so that a dual interpolation operation isemployed for a determination of the surge control function.

Once the combustor shell pressure is identified, the double linearinterpolation is made along and between the curves 326 and 328. If thecombustor shell pressure is below the point at which the coincidentportions 330 of the curves 326 and 328 become applicable, the ordinateof the applicable surge limit function is determined by intercurveinterpolation on the basis of measured compressor inlet temperature todefine the surge limit value of startup fuel demand. In order to makethe ordinate interpolation, interpolations are first made to determinepoints on the startup portions of the curves 326 and 328 correspondingto the measured combustor shell pressure. Surge limit determination isalso made by linear interpolation, and in this case double linearinterpolation, on the curve portions 330 during load operations, but theordinate interpolation is applied to common points to generate the samepoint. As a result of the nonlinear surge function implementation,closer operation to turbine design limits is enabled.

After determination of the surge control function, block 724 determineswhether the system is in operating Mode 1. If it is, block 726 isentered to provide for gas turbine acceleration control from ignitionspeed of approximately 1000 RPM to the top speed of 4894 RPM. Block 726provides for fuel demand signal tracking in the same manner as thatsubsequently described in connection with blocks 764 and 767 (FIG. 39)and further generates a temperature reference with the use of storedcurve data previously considered in connection with FIG. 16. Thetemperature reference curves 334 and 336 are nonlinear and respectivelyrepresent turbine discharge temperature conditions associated withrespective constant turbine inlet temperatures of 1200° F. and 1500° F.for normal and emergency startups as a function of combustor shellpressure. Five points are stored for each curve 334 or 336 as indicatedand linear interpolation is employed between points on the same curve asconsidered in connection with FIG. 15. To determine the currentapplicable temperature reference, the block 726 accordingly determinesthe acquired analog value of combustor shell pressure and whether thestartup is in a normal or in an emergency status. Gas turbine operationwith greater constancy of operation at design turbine inlet temperatureis better enabled by the use of a nonlinear temperature reference in theblock 726 and in block 792 subsequently considered.

Block 728 operates next in Mode 1 control to determine the speedreference for analog output to the speed control 324 from the computer304. As shown in greater detail in FIG. 38, the speed reference programblock 728 first provides for determining whether the gas turbine 104 isat top or substantially synchronous speed as indicated by block 730. Forthe top speed condition, the speed reference routine is bypassed asindicated by the reference character 732 and a return is made to theturbine control program execution. Below top speed, block 734 determineswhether an emergency start has been requested and if it has, block 736determines the change in the speed reference required for operationduring the next sampling time interval from data representative of thecurve 307 shown in FIG. 13. If a normal start has been requested, block738 determines the speed reference charge in accordance with datarepresentative of the curve 306 in FIG. 13.

As previously indicated, the nonlinear curves 306 and 307 respective andadvantageously provide for fixed normal and fixed emergency startuptimes while holding substantially constant turbine inlet gastemperature. The faster emergency startup curve 307 corresponds to ahigher turbine inlet temperature operation and, it may be noted, higherturbine temperature transients which produce greater stress damage tothe turbine parts. Although blade temperature or surge limit control maypossibly extend the startup period, the normal programmed fixed startuptime, in this case from ignition speed to synchronous speed, is normallyachieved to provide the previously considered advantages of fixed timestartup.

Each of the speed curves 306 or 307 in FIG. 13 is placed in core storagewith the use of five data points as indicated. The indicated speed curveslopes or accelerations corresponding to the denoted speed curve pointsare stored and a linear interpolation process is used to determineacceleration values at working time points between the time pointscorresponding to the stored curve points. As presented previously inconnection with parameter change entries into the computer 704, a speedreference change calculation for block 736 or 738 is based upon theslope of the speed curve at the next preceding sample time point and thechange in time associated with the next sample period (FIG. 54).

In block 740, the new speed reference is calculated by adding thecalculated small speed reference step change to the preceding speedreference. The acceleration formula set forth in connection withparameter changes applies to FIG. 54 and it is used in making the speedchange calculations. The speed reference algorithm previously noted inconnection with section B provides an underlying representation of thespeed reference generation.

Among other advantages associated with the speed reference generationscheme, the plant operator can switch between normal and emergency startprocedures at any time in the startup process with smooth transitionsince no large steps occur in the speed reference function andaccordingly no undesirable operating transients are imposed on the gasturbine 104. It is also noteworthy that a 0 speed change is added to thespeed reference when the HOLD pushbutton is pressed.

A top speed limit is next placed on the speed reference by block 742 ifblock 744 detects an excessive speed referene value. If the speedreference is not excessive or if the speed reference is set at topspeed, the speed reference value is stored and a return is made to theexecution of the control block 712.

Generally, the blade path temperature control loop responds faster thanthe exhaust temperature control loop and it is therefore the controllingfactor in Mode 1 control. The exhaust temperature control loop and theload limit control loop are both normally tracking the fuel demandsignal during Mode 1 control for reasons of control loop availability.FIG. 40B illustrates the conditions of the various control loopsconsidered during Mode 1 control.

As detailed in FIGS. 40B and 40C all control Modes including Mode 1employ a fuel demand limit check in the control path to keep the outputfuel demand signal within the range of 0 to 2.5 volts as indicated inblock 746. A multiplication by a factor of 2 is made in block 748 to putthe analog output signal in the range of 0 to 5 volts.

In execution of the block 744 in the temperature limit routine 744, adetermination is first made in block 746 of the temperature error bytaking the difference between the temperature reference previouslyderived in the block 726 (or the block 792 in FIG. 46) and the actualand preprocessed average blade path temperature. As shown in FIG. 41A,the software blade path temperature control configuration includes arate function 748 which is applied to the average blade path temperaturerepresentation. The temperature representation and its derivative areadded together in summer 750.

FIG. 53 shows the rate function and its software control channelinteraction in greater detail. Thus, after the necessary data isobtained, a decay term is calculated and if the temperature isincreasing a step term is determined and added to the decay term. If thetemperature is decreasing, no step term is used and the output is madeequal to the decay term. FIG. 45 illustrates the process employed fordifferentiation.

As a result, the summer 750 in FIG. 41A has a temperature value and atmost a remanent decay term applied to it during temperature drops sothat tracking is provided for decreasing temperature. On temperatureincreases, the summer 750 generates the sum of a temperature value and ainstantaneous step term and a decay term for anticipatory or predictivelimit control with rising blade path temperature.

To obtain backup transient temperature limit protection, a summer 752(FIG. 41A) provides a blade path offset to the temperature referencepreviously determined in the flowchart block 726 (FIG. 37) by an amountof 50° F. in control Modes 3 and 4 during which the slower respondingexhaust control channel provides primary temperature limit control, butno offset is made in control Modes 1 and 2. The preprocessing performedby blocks 748, 750 and 752 in the control configuration of FIG. 41A isperformed by the program block 746 in FIG. 39.

A predetermined deadband is applied to the determined blade pathtemperature error in block 754. If an error exists outside the deadbanddetermined in the block 754, its sign is determined in block 756. If theblade path temperature error is negative, control action is imposed byblock 758 with a proportional routine and an integral routine. The bladepath temperature and temperature error variables are then stored byblock 760 and block 762 sums the results of the proportional andintegral operations of block 758 to generate the blade path output limitrepresentation BPSGNL. If the blade path temperature errors is positive,block 764 obtains the fuel demand signal FDSIG or SCO in the hardwarespeed control 324, sets the blade path temperature error representationto zero and causes the reset function in block 758 to track the fueldemand signal (as indicated in the control configuration in FIG. 34).The blade path temperature representation is then kept slightly abovethe control signal output so that it is ready to take limit control ifrequired.

After execution of the block 762, the exhaust temperature control ortracking action is determined in a series of blocks similar to thosejust considered in connection with blade path temperature control andtracking action. However, block 765 provides no offset for thetemperature reference as indicated in the software control configurationfor exhaust temperature control shown in FIG. 41B. Further, a savevariables block 769 provides for storing the exhaust temperature errorand the track function output initiated by block 767. Block 760 alsosaves the blade path variables.

The tracking action provided for by blocks 764 and 767 in thetemperature limit loops enables the loops to enter their limit controlconfiguration with faster control action following a change intemperature error from positive to negative since the reset routines donot have to integrate back from some saturated output value. Inparticular, the tracking action is such that the reset block outputnever exceeds the fuel demand signal by more than a difference value, inthis case a value corresponding to 0.12 volts.

To obtain the tracking action, the desired difference value is added tothe low selected fuel demand signal and the result is differenced fromthe output of a reset or integrator routine and applied to the input ofthe reset routine. FIG. 44 shows the process employed for integration.The output of the integration operation accordingly tracks the fueldemand signal with a positive bias. The described tracking operationaccordingly allows the tracking control loop to enter quickly into fuelcontrol if required by a change in the error quantity controlled by thetracking control loop, yet the fuel signal tracking output of thetracking control loop is sufficiently high to provide some degree ofcontrol freedom for the control loop which is actively controlling fuelthrough the low fuel demand selector block 700 (software) or thehardware low select arrangement previously described.

After the exhaust temperature output limit is determined in block 766 areturn is made to the routine 712 in FIG. 37. Next, a software lowselection is made by block 700 in the Mode 1 control program execution.Repeated executions of the control routine 712 are made during the timeperiod that the gas turbine 104 is placed under sequencing andacceleration operations in Mode 1 control.

Once synchronous speed is reached, block 768 in FIG. 37 directs theprogram into Mode 2 control operations. In block 770, the speedreference is set equal to the top speed value plus any speed changeentered into the control loop by manual synchronization operations or byautomatic synchronization program execution. Further, the programoperations are redirected through blocks 726, 728, 744 and 700 as in thecase of Mode 1 control.

After synchronization, block 722 or 744 directs control programoperations to a Mode 3 control block 776 or a Mode 4 control block 778according to the operator's panel selection. As shown in greater detailin FIG. 46, the Mode 3 block 776 provides for determining kilowatt errorfrom the difference between the kilowatt reference and actual kilowattsin block 780. Proportional and integral controller routines are thenapplied to the kilowatt error in block 782 and the resultant controlleroutputs are summed in block 784 in order to provide for constantkilowatt control with temperature limit backup in Mode 3. The kilowattreference employed in the error determination block 780 is adjustablewith the RAISE and LOWER pushbuttons on the operator's panel.

A loading rate limit is determined by block 786 to prevent excessivethermal transients due to excessive loading rates under automatic ormanual incremental loading. The rate limit action is performed toproduce the loading rates previously described. As shown in FIG. 40D,the loading rate limiter is a function generator which tracks the fueldemand signal CSO with a positive bias for control availability duringnonramping periods. Once a load reference change is generated, theloading rate limiter adds a step term to its output to operate throughthe load and loading rate low select block (FIG. 40) and allow the fueldemand signal to ramp at the preset rate.

In FIG. 52, a relatively detailed flowchart is shown for the loadinglimit subroutine. If the control program is in Mode 1 or 2, the limiteroutput is made equal to LRMAX, i.e. tracking. If the control program isin Mode 3 or 4 and the limiter output is greater than or equal to LRMAX,the limiter is caused to track LRMAX. Otherwise the limiter output has astep term added to it and if the sum is less than LRMAX it is generated.However, if the sum is greater than or equal to LRMAX the limiter outputagain is caused to track the fuel demand signal. As shown, the size ofthe step term is different (higher) for emergency startups as comparedto normal startups.

When Mode 3 is first entered, the kilowatt reference is set at a minimumvalue and the operator can then determine the kilowatt reference valuethereafter. However, the reference cannot exceed that valuecorresponding to the base load exhaust temperature limit. The softwarecontrol configuration associated with Mode 3 is shown in FIG. 40C, andthe constant kilowatt control shown therein is illustrated in greaterdetail in FIG. 40D. As previously considered and as shown in FIG. 400,the primary Mode 3 controls are the exhaust temperature control and theconstant kilowatt control while the blade path and surge controlsprovide backup protection. The speed reference is set at a value of 106%rated speed to cause a speed error of 6% which is too high for selectionby the low selection software block. If the generator 102 isdisconnected from the system, the speed loop will regulate turbine speedto the 104% value with 2% droop to maintain the fuel level required foridle operation.

In Mode 4, the kilowatt reference is caused to track actual load andblock 786 then makes a loading rate limit determination. Low selectionblock 788 functions in Mode 3 to determine the lowest fuel demandcorresponding to the kilowatt control limit and the loading rate limitas previously considered but it simply passes the loading rate limit inMode 4. Block 790 provides for setting the speed reference to the106%value and the previously noted block 792 provides for determiningthe temperature reference with the use of the curves 334, 340 and 342(FIG. 17) as considered in connection with the Mode 1 control block 726for use in the blade path and exhaust temperature limit control block744.

In both Mode 3 and Mode 4, the block 744 is executed in the mannerconsidered previously in connection with Mode 1. Since no constantkilowatt function is provided for Mode 4, the block 744 provides fortemperature loading operation through exhaust temperature limit action.Under temperature control, the generated power varies with the ambientair temperature such that more power is generated with lower inlet airtemperature.

With respect to Mode 3, a 50° F. offset if provided for the blade pathcontrol function so that in the steady state the exhaust functionprovides control. However, the blade temperature control does protectagainst high and sudden temperature transients.

The software control configuration for Mode 4 is illustrated in FIG.40E. Load Mode 3 and load Mode 4 program executions are completedthrough low select block 700 which selects the lowest fuel demandrepresentation associated with the temperature, surge and load limits toprovide the control operations described. Control program executionthrough the blocks 766, and/or 738, 744 and 700 continues for theduration of Mode 3 or Mode 4 load control.

    ______________________________________                                        Special Macros for Control Program                                            ______________________________________                                        1. DIF   Differencing Blocks                                                   ##STR51##                                                                    Form: DIF PLUS,MINUS                                                          Comments:                                                                     Result is in AL upon exit from the macro. There is a built-in                 check for overflow. If overflow occurs, the output is set equal               to the maximum value of 2.0 per-unit (B 11) with sign in the                  direction that overflow occurred.                                             2. SUM   Summing Block                                                         ##STR52##                                                                    Form: SUM,N,I1,I2,I3,I4,I5                                                    Comments:                                                                     N is the number of inputs. Result's in AL upon exit. The overflow             check is built-in, and functions the same as the one in DIF.                  3. MPL   Multiply                                                              ##STR53##                                                                    Form: MPL   BY                                                                Comments:                                                                     The contents of the accumulator are multiplied by the contents                of BY and the product is left in the two permanent locations                  UPPER and LOWER. High order bits are in UPPER.                                4. DIV   Divide                                                                ##STR54##                                                                    Form: DIV BY                                                                  Comments:                                                                     The double length contents of the permanent locations UPPER                   and LOWER are divided by the contents of BY. The answer is                    stored in LOWER and the remainder is stored in UPPER.                         5. FID   1-Dimensional Function Generator                                      ##STR55##                                                                    Form: FID FNAME, XVALUE                                                       Comments:                                                                     The instructions for this macro cause the value contained in                  XVALUE to be stored in VARIN1, then there is a return jump to                 the 1-dimensional function generator subroutine 1DIMEN with                   the accumulator loaded with the address of the last independent               variable in the function table. The subroutine uses the information           given to find the value of the function corresponding                         to the value XVALUE. This value is in AL at the completion                    of the macro. The starting location                                           of the function table is specified by FNAME.                                  6. F2D   2-Dimensional Function Generator                                      ##STR56##                                                                    Form: F2D FNAME, XVALUE, YVALUE                                               Comments:                                                                     This macro stores XVALUE in VARIN1 and YVALUE in                              VARIN2 then it loads                                                          the accumulator with the address of                                           the last independent variable in the the function                             table. The subroutine uses this information to find the value of              the function corresponding to XVALUE and YVALUE.                              This value is in AL upon completion                                           of the macro. The starting location of the function table is given by         FNAME.                                                                        7. DFF   Differentiator or Rate Function                                       ##STR57##                                                                     ##STR58##                                                                    Form: DFF, GAIN OLDVAL, NEWVAL, OUTPUT                                        Comments:                                                                     This macro picks up the value for gain and does a return jump                 to the differentiator subroutine, DIFFER. Following                           the return jump are the addresses of the previous                             input value(OLDVAL), the address of the present                               input(NEWVAL) and the address of the output value(OUTPUT).                    The subroutine uses all this information to perform the numeric               operations to bring about the transfer function shown above.                  8. IGT   Integrator or Reset Function                                          ##STR59##                                                                     ##STR60##                                                                    Form: IGT, GAIN, OLDVAL, NEWVAL, OUTPUT                                       Comments:                                                                     The macro picks up the value for gain and return jumps                        to the integrator subroutine, INTEGR. Following                               the jump are the addresses of the previous                                    input value(OLDVAL), the present input(NEWVAL),                               and the output(OUTPUT). The subroutine uses this data to                      numerically effect the transfer function shown above.                         9. IFP   Positive Check                                                        ##STR61##                                                                    Form: IFP, LABEL                                                              Comments:                                                                     If the contents of the accumulator, AL, are positive,                         jump to LABEL.                                                                10. LOS   Low Select                                                           ##STR62##                                                                    Form: LOS A,B                                                                 Comments:                                                                     The macro finds the lower of the two values and leaves it in AL.              D. The Integrator or Reset Function Subroutine INTEGR                         This subroutine numerically performs the integration or reset                 control function using information furnished to it in the subroutine          call. The IGT macro is the subroutine call and has the form:                  ENJ   GAIN                                                                    RJP   INTEGR                                                                  OCT   OLDVAL Address of X(N - 1)                                              OCT   NEWVAL Address of X(N)                                                  OCT   OUTPUT Address of Y(N - 1)                                              The subroutine is entered with the GAIN in AL.                                Once this is divided by two and stored, the addresses                         of the other variables of interest are picked up and stored.                  The subroutine is now ready to begin the actual calculation.                  The algorithm used for the reset function is:                                  ##STR63##                                                                    where y(N), X(N) indicate the values at the Nth time                          sample and y(N - 1) indicates the value at the                                previous time sample. The subroutine does not                                 save or initialize the previous values needed for the                         calculation. This must be done as a part of the main program.                 In order to maintain accuracy the variables and gain are at a B               point of 11. The result is stored in the output address at B of 11.           Care is taken in the calculation to see that the B point is                   maintained.                                                                   E. The Differentiator or Rate Function Subroutine, DIFFER                     This subroutine numerically performs the differentiation or                   rate function using information contained in the subroutine call.             The call is contained in the DFF macro and has the form:                      ENL   GAIN                                                                    RJP   DIFFER                                                                  DEC   OLDVAL Address of X(N - 1)                                              DEC   NEWVAL Address of X(N)                                                  DEC   OUTPUT Address of Y(N - 1)                                              In this subroutine as in the reset subroutine,                                the calculations are done in fixed point at a B                               point of 11. The values stored in OLDVAL, NEWVAL, and                         OUTPUT are per-unit B 11. The value of GAIN                                   is at a B of 9. As long as the GAIN and the PERIOD                            are at the same B point, the answer will come out at the same B               point as the input. The algorithm used for this function is:                   ##STR64##                                                                     ##STR65##                                                                    This algorithm numerically calculates the s domain                            transfer function:                                                             ##STR66##                                                                    ______________________________________                                    

Note that the transfer function contains a damping term, 1/(1+(GAIN)s).This damping is desirable because a pure differentiating action ishighly sensitive to noise and may yield numerical instability. We willnow see how the subroutine does the calculation.

The first operations in the subroutine take the gain that is in AL andmultiply it by 2. Next, the addresses of the input variables are pickedup and stored in the subroutine area. All the data is now in for thecalculation. The calculation is done in two steps. The first stepcalculates the first term in the algorithm and the second stepcalculates the second term. These are summed and the result checked tosee if it exceeds the maximum value of 2.0 per-unit.

The final answer is stored in OUTLOC which up until the time of storagehas contained the previous output. The subroutine does not save orinitialize the values of the previous values; this must be done in themain program.

9. Alarm and Thermocouple Check Programs

In the alarm system, alarms are generated in response to sensorsconsidered in connection with FIG. 12. Printout of alarms is made as inthe following example:

    ______________________________________                                                           Turbine                                                    Time    Status     Identification                                                                              Description                                  ______________________________________                                        12:30   ALRM       A             Flame A                                      ______________________________________                                    

The status conditions of the alarms are listed below:

NORM--Normal

ALRM--Alarm

A flowchart for the alarm program 610 is shown in FIG. 47. Alarms aredetermined by the sequencing program 600 and the thermocouple checkprogram 616 as previously considered. A flowchart for the thermocouplecheck program 616 is shown in FIG. 48. Alarm printouts generated by thealarm program 610 result from the use of two tables of bits. In thefirst table, the bits are set On and OFF by the sequencing program 600and the thermocouple check program 616 and the second table is used tostore the previous condition of the alarm bits. The alarm program 610compares the two tables and generates alarm messages when the bitpatterns of the two tables differ. The alarm program 610 is periodicallyexecuted to print out all points in alarm as follows.

In the case of shutdown alarms, one operational and maintenanceadvantage associated with the operation of the control system 300 isthat the alarm condition which causes a shutdown can be readilydetermined. Thus, logic processing provided by the sequencing program inthe implementation of the sequence logic (FIG. 33) avoids the generationof multiple spurious alarms which are caused by the shutdown itself andfollow the shutdown causing alarm. Multiple confusing alarm lightings asencountered with conventional annunciator panels are thus avoided.

    ______________________________________                                        3.6 ALARMS-AUXILIARIES                                                                          Generator                                                                     Trip       Alarm                                            ______________________________________                                        A.  Generator - 87-64G-40                                                                             X            X                                            46-51V-67                                                                     81G-27G                                                                       87T                                                                       B.  Generator Bus Grd   X            X                                        C.  Generator 81B       X            X                                            27B                                                                       D.  Generator 60 CFVB   X            X                                        E.  Generator Optional Alarms                                                     1. Ground           X            X                                            2. Differential                                                               3. Loss of Field                                                              4. Reverse Power                                                              5. Negative Sequence                                                                              X            X                                            6. Over Current                                                               7. Exciter Field Ground                                                       8. Aux. Transformer Alarm                                                 F.  Transformer SPR Relay                                                                             X            X                                            Oil Temperature                                                               Oil Level                                                                     Miscellaneous                                                             G.  Transformer Optional Alarms                                                                       X            X                                            1. Hot Spot                                                                   2. Oil Flow                                                                   3. Instrument Air                                                         ______________________________________                                        3.7 STARTING AND RUNNING SHUT DOWN                                                               Local   Remote                                                                Start                                                                              Run    Start  Run                                     ______________________________________                                        Blade Path Overtemperature                                                                         SD     SD     SD   SD                                    Turbine Exhaust Overtemperature                                                                    SD     SD     SD   SD                                    (Manifold)                                                                    Low Lube Oil Pressure                                                                              SD     SD     SD   SD                                    Low Fuel Supply Pressure(Gas)                                                                      SD     SD     SD   SD                                    (PS9GL)                                                                       Turbine Overspeed    SD     SD     SD   SD                                    Loss of Computer     SD     SD     SD   SD                                    Low DC Control Voltage(BUS)                                                                        SD     SD     SD   SD                                    LDC (Charger)                                                                 High Vibration (Run)50 to                                                                          SD     SD     SD   SD                                    100% Speed                                                                    High Bearing Temperature                                                                           SD     SD     SD   SD                                    Fire Detection(FR1, FR2)                                                                           SD     SD     SD   SD                                    Low Compressor Suction                                                                             A      A      SD   SD                                    Low Lube Oil Level   A      A      SD   SD                                    High Lube Oil Temperature                                                                          A      A      A    SD                                    Low Instrument Air Pressure(PS11)                                                                  A      A      SD   SD                                    High Vibration(Start)0-50% Speed                                                                   SD     A      SD   A                                     Loss DC to Auxiliary Pump                                                                          SD     A      SD   A                                     Unit Not on Turning Gear(start & Stop)                                                             SD     --     SD   --                                    Sequence Failure     SD     --     SD   --                                    Loss of Starting Device(Active to 50%)                                                             SD     --     SD   --                                    Combustor Outfire #1 6A, 6B                                                                        SD     SD     SD   SD                                    Combustor Outfire #2 7A, 7B                                                                        SD     SD     SD   SD                                    #1 Bleed Valve Position Failure                                                                    SD     --     SD   --                                    to Open(Start)                                                                #1 Bleed Valve Position-Failure to Close                                                           A      A      A    A                                     #2 Bleed Valve Position-Failure                                                                    SD     --     SD   --                                    to Open(Start)                                                                #2 Bleed Valve Position-                                                                           A      A      A    A                                     Failure to Close                                                              Fuel Supply Pressure High(Gas)                                                                     SD     A      SD   A                                     (PS9GH)                                                                       Emergency Stop-(PS & G Cabinet)                                                                    SD     SD     SD   SD                                    Remote Stop          SD     SD     SD   SD                                    Local Stop           SD     SD     SD   SD                                    Low Fuel Oil Supply Pressure                                                                       SD     SD     SD   SD                                    (PS9DS)                                                                       High Fuel Oil Pressure(PS9D)                                                                       SD     --     SD   --                                    Low Fuel Oil Pressure(PS9D)                                                                        --     SD     --   SD                                    Inlet Guide Vane Fail to Open                                                                      A      A      A    A                                     (Start & Run)                                                                 Inlet Guide Vane Fail to Close(Start)                                                              SD     --     SD   --                                    Exhaust Overtemperature                                                                            SD     SD     SD   SD                                    Disc Cavity Area 1 O.T.                                                                            A      A      A    A                                     Disc Cavity Area 2 O.T.                                                                            A      A      A    A                                     Disc Cavity Area 3 O.T.                                                                            A      A      A    A                                     Disc Cavity Area 4 O.T.                                                                            A      A      A    A                                     Disc Cavity Areas 1"4(2 in                                                                         SD     SD     SD   SD                                    Same Area)                                                                    High Temperature Inlet of                                                                          SD     SD     SD   SD                                    of Main Pump                                                                  ______________________________________                                         A  Alarm Only                                                                 SD  Alarm and Shutdown                                                   

The thermocouple check program 616 also runs on a periodic basis. Whenit is executed, a check is made of the values stored for allthermocouples not checked by the control program 602 to determine if thethermocouple value is more negative than a predetermined check numberstored in location CHKNO. An excessive negative number is considered anopen circuit and an alarm bit is set for the alarm program 610.

10. Data Logging Program

A formated log is printed in response to execution of the log program618 on a periodic basis selected by the plant operator within the rangeof 15 minutes to two hours. The printed readings are instantaneousvalues obtained from the last analog scan cycle. The plant operatorselects any 20 analog points per turbine under control, such as the moreuseful analog points included in the following:

    ______________________________________                                        (1)   (10)     points-Bearing temperatures.                                   (2)   (2)      points-compressor inlet and discharge air                                     temperature                                                    (3)   (1)      point-lube oil cooler discharge temperature                    (4)   (2)      points-generator air cooler in and out                                        temperature                                                    (5)   (8)      points-disc cavity temperature                                 (6)   (8)      points-blade plate temperature                                 (7)   (8)      points-exhaust manifold temperature                            (8)   (4)      points-vibration                                               (9)   (1)      point-speed                                                    (10)  (1)      point-watt                                                     (11)  (1)      point-for VARS                                                 (12)  (1)      point-volts                                                    (13)  (1)      point-amperes                                                  (14)  (1)      point-frequency                                                (15)  (6)      points-RTD for generator temperature.                          ______________________________________                                    

A flowchart is shown for the log program 618 in FIG. 49.

The conversion program 620 is illustrated by flowcharts shown in FIGS.50A, B, C and D. Generally, the analog conversion program 620 providesfor converting entered analog values into the engineering valuerepresented by the input and vice versa. Generally, four types ofconversion are provided, i.e., flow straight-line, thermocouple, andsegmented straight-line.

11. Miscellaneous Programs

The miscellaneous programs 622 includes a programmer's console functionprogram for converting engineering units to values corresponding to theanalog input system as shown in FIG. 51. It is essentially the reverseof the analog conversion program 620 and provides for convenientoperator communication with the computer through the teletypewriter orprinter. For example, alarm setpoint limits can be conveniently adjustedin the sequencing program 600 with the use of the engineering units toanalog conversion program. A flowchart 800 is shown in FIG. 51 for theengineering units to analog conversion program.

Other programs includes in the miscellaneous category are a deadswitchcomputer program which verifies that certain basic functions of thecomputer are operating as expected. A power failure and restart programinterfaces with the executive program 604 to save registers and stop thecomputer 304 when a power failure interrupt is received, and it restartsthe main computer subsystems when the power supply voltage is returnedto normal.

E. LIST OF MACROS, INPUTS/OUTPUTS AND PROGRAMS WRITTEN IN ASSEMBLYLANGUAGE (NOT PRINTED)

The deposited microfiche appendix, cross-referenced before, discloses aprintout of a listing which includes the logic and control Macros, thecontact closure inputs and outputs, the analog inputs and the devicesassociated with sequencing control in a specific embodiment of thecontrol system 300 shown in FIG. 12. The deposited listing also includesa printout of specific programs employed in the embodiment. The programsystem described in section D hereof substantially embraces the programsin the listing. Generally, the programs were written in assemblylanguage and stored in a P50 core memory 16K in size. With morejudicious use of core areas and increased use of subroutining, it isexpected thsat substantially the same subject matter and relatedadditions can be programmed in less than 12K of core memory.

Although the detailed flowcharting corresponding to the program printoutdoes have certain differences from certain aspects of the describedflowcharting, the listed programs do provide for an essentialimplementation of the subject matter described herein. Generally, inaddition to being embraced by the described program system as alreadyindicated, the programs are arranged for application in the control looparrangement 300A (FIG. 34) as embodied in the control system 300 (FIG.12).

Most developed system software may be characterized with relativelyminor faults known as bugs which sometimes take long periods of time todetect and/or diagnose. Ordinarily, the correction of such faults iswithin the skill of control and system programmers. The program listingwhich follows accordingly may be expected to contain some faults of thiskind but all such faults which have been detected have required onlyprogrammer skill for correction in field applications.

As an aid to the reader, the following notes are made relative to theformat of the program listing:

a. The first line on each page contains the title of the program and/orthe page number for that program.

b. The first column of octal digits is a sequential record numberlisting corresponding to the punched card or other program inputrecords.

c. The second column of five octal digits is a machine languagestatement of the memory address of the instruction which is described onthat line.

d. Each row in the third column of six octal digits is separated intofields of two digits, one digit and three digits, and it expresses thecontents of the memory address separated into the instruction format.The fields contain:

1. Operation code--left two digits

2. Addressing mode--middle, single digit

3. Operand address--right three digits.

e. The fourth column of one mark, i.e., or √, indicates that an addressor value was generated by the assembler to satisfy the requestedinstructions.

f. Each row in the fifth column up to six characters, letters ornumerals contains the symbolic title assigned to the correspondingmemory address by the programmer in the assembly language.

g. Each row in the sixth column of three letters contains the operationcode assigned to the corresponding memory address by the programmer inthe assembly language. The operation code includes a large number ofdirectives to the assembler program and the various available machineinstructions.

h. Each row in the seventh column of up to six characters represents theoperand address assigned to the corresponding memory location by theprogrammer in the assembly language.

i. The remaining columns contain comments made by the programmer to aidin understanding the program operation.

What is claimed is:
 1. A combustion turbine electric power plantcomprising a combustion turbine having a compressor and combustion andturbine elements, a generator having a field winding and being coupledto said combustion turbine for drive power, a fuel system for supplyingfuel to the combustion turbine combustion element, means for excitingsaid generator field winding, a control system including digitalcomputer means and signal input/output means therefor, means foroperating said fuel system to energize said turbine and for controllingsaid exciting means, means for generating a turbine speed and otherpredetermined feedback signals, means for operating said computer meansto make control action determinations for implementation by said fuelsystem operating means and said exciting control means, said computeroperating means generating a feed forward speed reference representationas one of said control action determinations, said computer operatingmeans further generating a turbine load level determining representationin response to at least one of said other predetermined turbine signals,said computer operating means combining said representations to generatea fuel demand,and means external to said computer means for controllingsaid fuel system operating means in response to the fuel demand and saidspeed signal means for turbine and generator speed control.
 2. Acombustion turbine electric power plant comprising a combustion turbinehaving a compressor and combustion and turbine elements, a generatorcoupled to said combustion turbine for drive power, a generator breakerfor coupling said generator to a power system, a fuel system forsupplying fuel to said combustion turbine combustion element, a controlsystem including digital computer means and signal input/output meanstherefor, means for controlling and operating said fuel system toenergize said turbine, means for generating a turbine speed and therpredetermined feedback signals, means for operating said computer meansto make control action determinations for implementation by said fuelsystem operating means and to control the opening and closure of saidgenerator breaker, said computer operating means generating a feedforward speed reference representation as one of said control actiondeterminations, said computer operating means further generating aturbine load level determining representation in response to at leastone of said other predetermined turbine signals, said computer operatingmeans combining said representations to generate a fuel demand, andmeans external to said computer means for controlling said fuel systemoperating means in response to the fuel demand and said speed signalgenerating means for turbine and generator speed control.
 3. An electricpower plant as set forth in claim 2 wherein said computer operatingmeans generates said load level representation as a function of anonlinear turbine operating limit characterization.
 4. A method ofoperating an electric power plant including a gas turbine havingcompressor, combustion and turbine elements, a generator coupled to theturbine for drive power, a fuel system for supplying fuel to the gasturbine combustion element, means for operating the fuel system toenergize the turbine, a programmable digital computer and aninput/output system therefor, the steps of said method comprising:(a)operating the computer to generate a fuel demand representation fordesired turbine operation characterized in accordance with the nonlinearresponse characteristics of the turbine; (b) converting said computerdetermined fuel demand representation to an analog signal; (c) utilizingsaid analog signal as a feedforward speed/load fuel demand signal forthe turbine and driven generator; (d) operating the computer to generatea plurality of generator and turbine parametric fuel demand limitrepresentations; (e) utilizing said developed parametric representationsto limit and calibrate, where necessary, said feedforward speed/loadfuel demand signal over the entire range of expected plant operation;and (f) utilizing said limited feedforward speed/load fuel demand signalto control the means for operating the fuel system.
 5. An electric powerplant as set forth in claim 3 wherein said computer operating meansdetermines an operating limit representation for an exhaust temperaturelimit based on a function of determining exhaust temperature and anonlinear temperature reference characterization applicable duringturbine startup and load operation and in addition an operating limitrepresentation for a nonlinear surge limit characterization applicableduring turbine startup.
 6. An electric power plant as set forth in claim5 wherein means are provided for detecting generator load and saidcomputer operating means further provides for controlling said fuelsystem operating means in response to detected load to regulate thegenerator load substantially to a predetermined value.
 7. An electricpower plant as set forth in claim 6 wherein means are provided forlimiting the rate at which said fuel demand representation changesduring load operating level changes.
 8. An electric power plant as setforth in claim 2 wherein means are provided for detecting genrator loadand said computer operating means further provides for controlling saidfuel system operating means in response to detected load to regulate thegenerator load substantially to a predetermined value and wherein meansare provided for limiting the rate at which said fuel demandrepresentation changes during load operating level changes.
 9. Acombustion turbine electric power plant comprising a combustion turbinehaving a compressor and combustion and turbine elements and having speedand load modes of operation, a generator having a field winding andbeing coupled to said combustion turbine for drive power, a fuel systemfor supplying fuel to the combustion turbine combustion element, meansfor exciting said generator field winding, a control system includingdigital computer means and signal input/output means therefor, means foroperating said fuel system to energize said turbine and for controllingsaid exciting means, means for generating a turbine speed signal andother predetermined feedback signals, means for operating said computermeans to make control action determinations for implementation by saidfuel system operating means and said exciting control means, saidcomputer operating means generating a fuel demand for turbine speed andload control in response to a turbine speed demand and a turbine loaddemand or limit, means for generating at least one of said speed andload demand signals in response to a nonlinear turbine operating limitcharacterization, and means for controlling said fuel system operatingmeans in response to a computer means output signal corresponding tosaid fuel demand.
 10. An electric power plant as set forth in claim 9wherein the characterization is for an exhaust temperature limited basedon a function of determined exhaust temperature and a nonlineartemperature limit reference applicable during turbine startup and loadoperation.
 11. An electric power plant as set forth in claim 9 whereinthe characterization is for a non-linear surge limit which operates insaid generating means at least during the startup mode of operation. 12.An electric power plant as set forth in claim 9 wherein means areprovided for detecting generator load and said computer operating meansfurther provides for controlling said fuel system operating means inresponse to detected load to regulate the generator load substantiallyto a predetermined value.
 13. An electric power plant as set forth inclaim 12 wherein means are provided for incrementally varying thepredetermined value to which the load is regulated.
 14. An electricpower plant as set forth in claim 9 wherein means are provided fordetecting generator load and said computer operating means furtherprovides for controlling said fuel system operating means in response todetected load to regulate the generator load substantially to apredetermined value and wherein means are provided for limiting the rateat which said fuel demand representation changes during load operatinglevel changes.
 15. An electric power plant as set forth in claim 9wherein said computer operating means determines an operating limitrepresentation for an exhaust temperature limit based on a function ofdetermining exhaust temperature and a nonlinear temperature referencecharacterization applicable during turbine startup and load operationand in addition an operating limit representation for a nonlinear surgelimit characterization applicable during turbine startup.
 16. Acombustion turbine electric power plant comprising a combustion turbinehaving a compressor and combustion and turbine elements, a generatorcoupled to said combustion turbine for drive power, a generator breakerfor coupling the generator to a power system, a fuel system forsupplying fuel to the combustion turbine combustion element, a controlsystem including digital computer means and signal input/output meanstherefor, means for controlling and operating said fuel system toenergize said turbine, means for generating a turbine speed and otherpredetermined feedback signals, means for operating said computer meansto make control action determinations for implementation by said fuelsystem operating means and to control the opening and closure of saidgenerator breaker, said computer operating means generating a feedforward speed reference representation as one of said control actiondeterminations, said computer operating means further generating aturbine load level determining representation in response to at leastone of said other predetermined turbine signals, said computer operatingmeans combinining said representations to generate a fuel demand, andmeans external to said computer means for generating at least one ofsaid speed and load demand signals in response to a nonlinear turbineoperating limit characterization, and means for controlling said fuelsystem operating means in response to a computer means output signalcorresponding to said fuel demand.
 17. An electric power plant as setforth in claim 16 wherein the characterization is for an exhausttemperature limit based on a function of determined exhaust temperatureand a nonlinear temperature limit reference applicable during turbinestartup and load operation.
 18. An electric power plant as set forth inclaim 16 wherein the characterization is for a nonlinear compressorsurge limit which operates in said generating means at least during thestartup mode of operation.
 19. An electric power plant as set forth inclaim 16 wherein said computer operating means determines an operatinglimit representation for an exhaust temperature limit based on afunction of determined exhaust temperature and a nonlinear temperaturereference characterization applicable during turbine startup and loadoperation and in addition an operating limit representation for anonlinear surge limit characterization applicable during turbinestartup.
 20. An electric power plant as set forth in claim 16 whereinmeans are provided for detecting generator load and said computeroperating means further provides for controlling said fuel systemoperating means in response to detected load to regulate the generatorload substantially to a predetermined value and wherein means areprovided for limiting the rate at which said fuel demand representationchanges during load operating level changes.
 21. An electric power plantas set forth in claim 16 wherein said computer operating meansdetermines a fuel demand representation for desired turbine operation,said fuel demand representation includes a speed demand representationwhich is converted to an analog output speed reference signal from saidcomputer means, and said fuel system controlling means includes meansfor detecting actual turbine speed and means for generating a fueldemand signal in response to the difference between the actual speed andthe speed reference.
 22. An electric power plant as set forth in claim21 wherein the fuel demand representation includes a plurality of fueldemand limit representations, and means are provided for selecting thelowest fuel demand signal or representation as said fuel demand signalgenerating means.
 23. An electric power plant as set forth in claim 21wherein means are provided for detecting generator load and saidcomputer operating means further provides for controlling said fuelsystem operating means in response to detected load to regulate thegenerator load substantially to a predetermined value.
 24. An electricpower plant as set forth in claim 22 wherein means are provided fordetecting generator load and said computer operating means furtherprovides for controlling said fuel system operating means in response todetected load to regulate the generator load substantially to apredetermined value.
 25. An electric power plant as set forth in claim23 wherein means are provided for limiting the rate at which said fueldemand representation changes during load operating level changes. 26.An electric power plant as set forth in claim 24 wherein means areprovided for limiting the rate at which said fuel demand representationchanges during load operating level changes.
 27. A combustion turbineelectric power plant comprising a combustion turbine having a compressorand combustion and turbine elements, a generator coupled to saidcombustion turbine for drive power, a generator breaker for coupling thegenerator to a power system, a fuel system for supplying fuel to the gasturbine combustion element, a control system including digital computermeans and signal input/output means therefor, means for controling andoperating said fuel system to energize said turbine, means forgenerating a turbine speed and other predetermined feedback signals,means for operating said computer means to make control actiondeterminations for implementation by said fuel system operating meansand to control the opening and closure of said generator breaker, saidcomputer operating means generating a feed forward speed referencerepresentation as one of said control action determinations, saidcomputer operating means further generating a turbine load leveldetermining representations in response to at least one of said otherpredetermined turbine signals, said computer operating means combiningsaid representations to generate a fuel demand, means external to saidcomputer means for controlling said fuel system operating means inresponse to the fuel demand and said speed signal means for turbine andgenerator speed control, means for detecting generator load, saidcomputer operating controlling said fuel system operating means inresponse to detected load to regulate the generator load substantiallyto a predetermined value, and means for limiting the rate at which saidfuel demand changes during load operating level changes.
 28. An electricpower plant as set forth in claim 27 wherein means are provided forincrementally varying the predetermined value to which the load isregulated.
 29. A combustion turbine electric power plant comprising acombustion turbine having compressor, combustion and turbine elements, agenerator coupled to said gas turbine for drive power, a fuel system forsupplying fuel to said combustion turbine combustion element, means foroperating said fuel system to energize said turbine, programmabledigital computer means and signal input/output means therefor, means forgenerating a turbine speed and other predetermined feedback signals,means for operating said computer means to generate a feedforward speeddemand representation for desired turbine operation, said computeroperating means further generating a turbine load level determiningrepresentation in response to at least one of said other predeterminedturbine signals, said computer operating means combining saidrepresentations to generate a fuel demand, and circuit means external tosaid computer for controlling said fuel system operating means inaccordance with said speed signal and a computer means output signalcorresponding to said fuel demand.
 30. A combustion turbine power plantas set forth in claim 29 wherein said fuel demand representationincludes a speed demand representation and said fuel system controllingcircuit means includes means for converting said speed demandrepresentation to an analog speed reference signal, and means forgenerating a fuel demand signal in response to the difference betweenactual speed and said analog speed reference signal.
 31. A combustionturbine power plant as set forth in claim 30 wherein said fuel demandrepresentation includes a plurality of fuel demand limitrepresentations, and wherein there is further provided selection meansfor selecting the lowest fuel demand signal or representation as theoutputfuel demand.
 32. An electric power plant as set forth in claim 31wherein said demand limit representation comprises a surge limitrepresentation of a nonlinear surge limit characterization applicableduring turbine startup.
 33. An electric power plant as set forth inclaim 30 wherein said fuel system controlling circuit means furthercomprises means for generating an auxiliary backup speed signal andmeans for limiting said fuel demand signal as a function of said backupspeed signal.
 34. An electric power plant as set forth in claim 29 whichfurther comprises means for limiting the rate at which said fuel demandrepresentation changes during load operating level changes.
 35. Anelectric power plant as set forth in claim 34 wherein said fuel demandrepresentation includes a speed demand representation and said fuelsystem controlling circuit means includes means for converting saidspeed demand representation to an analog speed reference signal, meansfor detecting actual turbine speed and means for generating a fueldemand signal in response to the difference between actual speed andsaid analog speed reference signal.
 36. An electric power plant as setforth in claim 35 wherein said fuel demand representation furtherincludes at least one fuel demand limit representation, and whereinthere is further provided selection means for choosing a fuel demandsignal in accordance with the lowest fuel demand signal orrepresentation.
 37. A plurality of combustion turbine electric powerplants comprising a separate combustion turbine for each plant havingcompressor and combustion and turbine elements, a generator for eachplant coupled to the associated combustion turbine for drive power,respective fuel systems for supplying fuel to the respective combustionelements, digital computer means and signal input/output means therefor,means for controlling and operating each of said turbine fuel systems,means for operating said computer means to make control actiondetermination for implementation by the respective fuel system operatingmeans, said fuel demand representation including a speed demandrepresentation which is converted to an analog output speed referencesignal from said computer means, and said fuel system controlling meansincluding means for detecting actual turbine speed and means forgenerating a fuel demand signal in response to the difference betweenthe actual speed and the speed reference.
 38. A plurality of combustionturbine electric power plants as set forth in claim 37 wherein the fueldemand representation further includes at least one fuel demand limitrepresentation, and means are provided for operating said fuel demandsignal generating means in accordance with the lower fuel demand signalor representation.
 39. A plurality of combustion turbine electric powerplants as set forth in claim 38 wherein each of said power plantsincludes a generator breaker for coupling the generator to a powersystem and said computer operating means further provides control actiondeterminations to control the opening and closure of each of saidgenerator breakers.
 40. A plurality of combustion turbine electric powerplants as set forth in claim 39 wherein means are provided for detectinggenerator load and said computer operating means further provides forcontrolling said fuel system operating means in response to detectedload to regulate the generator load substantially to a predeterminedvalue.
 41. A plurality of combustion turbine electric power plants asset forth in claim 40 wherein means are provided for limiting the rateat which said fuel demand representation changes during load operatinglevel changes.
 42. A plurality of combustion turbine electric powerplants as set forth in claim 39 wherein each of said power plantsincludes a generator breaker for coupling the generator to a powersystem and said computer operating means further provides control actiondeterminations to control the opening and closure of each of saidgenerator breakers.
 43. A plurality of combustion turbine electric powerplants as set forth in claim 42 wherein means are provided for detectinggenerator load and said computer operating means further provides forcontrolling said fuel system operating means in response to detectedload to regulate the generator load substantially to a predeterminedvalue.
 44. A plurality of combustion turbine electric power plants asset forth in claim 43 wherein means are provided for limiting the rateat which said fuel demand representation changes during load operatinglevel changes.
 45. A combustion turbine electric power plant comprisinga combustion turbine having compressor, combustion and turbine elements,a generator coupled to said combustion turbine for drive power, a fuelsystem for supplying fuel to said combustion turbine combustion element,means for operating said fuel system to energize said turbine,programmable digital computer means and signal input/output meanstherefor, means for operating said computer means to determine a fueldemand representation for desired generator load conditions, means fordetecting generator load, circuit means external to said computer meansfor controlling said fuel system operating means in response to thedifference between detected load and said fuel demand representation toregulate generator load substantially to a predetermined value, meansfor generating as a part of said fuel demand representation afeedforward speed demand representation, said fuel system controllingcircuit means including means for converting said speed demandrepresentation to an analog speed reference signal during speed controloperations, means for detecting actual turbine speed, and means forgenerating a fuel demand signal in response to the difference betweenactual speed and said analog speed reference signal.
 46. A combustionturbine electric power plant as set forth in claim 45 wherein said fueldemand representation further includes at least one fuel demand limitrepresentation, and wherein there is further provided selection meansfor choosing a fuel demand signal in accordance with the lowest fueldemand signal or representation.
 47. A plurality of gas turbine electricpower plants as set forth in claim 45 wherein means are provided forincrementally varying the predetermined value to which the load isregulated.
 48. An electric power plant as set forth in claim 45 whereinsaid computer operating means additionally determines a load rate limitfor limiting the rate at which said fuel system operating means canchange the fuel flow rate during load level operating changes.
 49. Anelectric power plant as set forth in claim 45 which further comprisesmeans for generating a surge limit representation of a nonlinear surgelimit characterization applicable during turbine startup, and saidcontrolling means further operates said fuel system operating means as afunction of said nonlinear surge limit representation.
 50. An electricpower plant as set forth in claim 45 wherein means are provided forgenerating a turbine exhaust temperature limit representation as afunction of an actual exhaust temperature representation and arepresentation of a nonlinear temperature reference characterization,applicable during startup operations, and said controlling means furtheroperates said fuel system operating means as a function of saidnonlinear temperature limit.
 51. An electric power plant as set forth inclaim 50 wherein means are further provided for generating a turbineexhaust temperature limit representation as a function of an actualexhaust temperature representation and a representation of a nonlineartemperature reference characterization, applicable during loadoperation.
 52. A combustion turbine electric power plant comprising acombustion turbine having compressor, combustion and turbine elements, agenerator coupled to said combustion turbine for drive power, a fuelsystem for supplying fuel to said combustion turbine combustion element,means for operating said fuel system to energize said turbine,programmable digital computer means and signal input/output meanstherefor, means for operating said computer means to determine a fueldemand representation for desired generator load conditions, means fordetecting generator load, circuit means external to said computer forcontrolling said fuel system operating means in response to thedifference between detected load and said fuel demand representation toregulate generator load substantially to a predetermined value, andmeans for incrementally varying the predetermined value to which theload is regulated.
 53. An electric power plant as set forth in claim 52wherein said computer operating means additionally determines a loadrate limit for limiting the rate at which said fuel system operatingmeans can change the fuel flow rate during load level operating changes.54. A combustion turbine power plant comprising a combustion turbinehaving a compressor and combustion and turbine elements, a generatorcoupled to said combustion turbine for drive power, a generator breakerfor coupling the generator to a power system, a fuel system forsupplying fuel to the combustion turbine combustion element, a controlsystem including digital computer means and signal input/output meanstherefor, means for controlling and operating said fuel system toenergize said turbine, means for generating a turbine speed and otherpredetermined feedback signals, means for operating said computer meansto make control action determinations for implementation by said fuelsystem operating means and to control the opening and closure of saidgenerator breaker, said computer operating means generating a feedforward speed reference representation as one of said control actiondeterminations, said computer operating means further generating aturbine load level determining representations in response to at leastone of said other predetermined turbine signals, said computer operatingmeans combining said representations to generate a fuel demand, meansexternal to said computer means for controlling said fuel systemoperating means in response to the fuel demand and said speed signalmeans for turbine and generator speed control, means for detectinggenerator load, said computer operating means controlling said fuelsystem operating means in response to detected load to regulate thegenerator load substantially to a predetermined value, and means forincrementally varying the predetermined value to which the load isregulated.
 55. A combustion turbine electric power plant comprising acombustion turbine having compressor, combustion and turbine elements, agenerator coupled to said gas turbine for drive power, a fuel system forsupplying fuel to said combustion turbine combustion element, means foroperating said fuel system to energize said turbine, programmabledigital computer means and signal input/output means therefor, means foroperating said computer means to determine a feedforward speed fueldemand representation and a variable load fuel demand representation fordesired plant operating conditions, circuit means external to saidcomputer for controlling said fuel system operating means in accordancewith said speed fuel demand representation, means for controlling saidfuel system operating means in accordance with said load fuel demandrepresentation to control generator load, and means for limiting therate at which said load fuel demand representation changes during loadoperating level changes.
 56. An electric power plant as set forth inclaim 55 wherein said limiting means applies one limit rate for normalloading and a higher limit rate for emergency loading.
 57. A combustionturbine power plant comprising a gas turbine having a compressor andcombustion and turbine elements, a generator coupled to said combustionturbine for drive power, a generator breaker for coupling the generatorto a power system, a fuel system for supplying fuel to the combustionturbine combustion element, a control system including digital computermeans and signal input/output means therefor, means for controlling andoperating said fuel system to energize said turbine, means forgenerating a turbine speed and other predetermined feedback signals,means for operating said computer means to make control actiondeterminations for implementation by said fuel system operating meansand to control the opening and closure of said generator breaker, saidcomputer operating means generating a feed forward speed referencerepresentation as one of said control action determinations, saidcomputer operating means further generating a turbine load leveldetermining representations in response to at least one of said otherpredetermined turbine signals, said computer operating means combiningsaid representations to generate a fuel demand, means external to saidcomputer means for controlling said fuel system operating means inresponse to the fuel demand and said speed signal means for turbine andgenerator speed control, and said computer operating means determining aload rate limit for limiting the rate at which said fuel systemoperating means can change the fuel flow rate during load leveloperating changes.
 58. An electric power plant as set forth in claim 57wherein said computer operating means further a feedforward speedreference representation, and means for controlling said fuel systemoperating means in response to the speed reference representation forturbine and generator speed control.
 59. An electric power plant as setforth in claim 57 wherein said computer operating means further providesfor determining at least one operating limit representation of anonlinear turbine operating limit characterization applicable over atleast one mode of the turbine operation, and means for controlling saidfuel system operating means as a function of the nonlinearrepresentation.
 60. A combustion turbine electric power plant comprisinga combustion turbine having compressor, combustion and turbine elements,a generator coupled to said combustion turbine for drive power, a fuelsystem for supplying fuel to said combustion turbine combustion element,means for operating said fuel system to energize said turbine, anoperator panel having predetermined generator and gas turbine switchesand indicating devices, programmable digital computer means and signalinput/output means therefor, means for operating said computer means inaccordance with predetermined generator and turbine parameters todetermine a fuel demand representation for desired turbine operation,means including said computer operating means for entering parameterchanges from said panel, means for controlling said fuel systemoperating means in accordance with said fuel demand representation, andmeans including said computer operating means for selectively displayingany of predetermined generator and turbine variables on each of at leastsome of the panel indicating devices.
 61. An electric power plant as setforth in claim 60 wherein means including said computer operating meansare provided for selectively displaying any of said predeterminedgenerator and turbine parameters on each of at least some of said panelindicating devices.
 62. A combustion turbine electric power plantcomprising a combustion turbine having compressor, combustion andturbine elements, a generator coupled to said combustion turbine fordrive power, a fuel system for supplying fuel to the combustion turbinecombustion element, means for operating said fuel system to energizesaid turbine, means for generating a turbine speed signal and otherpredetermined turbine feedback signals, means for generating afeedforward speed reference representation as a function of apredetermined acceleration reference representation, means for a turbineload level determining representations in response to at least one ofsaid other predetermined turbine signals, means for combining saidrepresentations to generate a fuel demand, and means for controllingsaid fuel system operating means in response to said fuel demandrepresentation for turbine and generator speed control.
 63. An electricpower plant as set forth in claim 62 wherein a first speed reference isgenerated from a first acceleration reference for normal startup and asecond faster speed reference is generated from a second accelerationreference for emergency startup.
 64. An electric power plant as setforth in claim 62 wherein said generating means comprises programmabledigital computer means having the acceleration reference representationin storage, and means are provided for operating said computer means todetermine said speed reference from said acceleration reference.
 65. Agas turbine electric power plant comprising a combustion turbine havingcompressor, combustion and turbine elements, a generator coupled to saidcombustion turbine for drive power, a fuel system for supplying fuel tosaid combustion turbine combustion element, means for operating saidfuel system to energize said turbine, means for generating a turbineexhaust temperature limit representation as a function of an actualexhaust temperature representation and a representation of a nonlineartemperature reference characterization, applicable during startupoperation, and means for controlling said fuel system operating means asa function of said nonlinear temperature limit.
 66. An electric powerplant as set forth in claim 65 wherein said controlling means includes ablade path temperature limit control arrangement and an exhausttemperature limit control arrangement and said nonlinear temperaturereference is employed in both control arrangements.
 67. An electricpower plant as set forth in claim 65 wherein said nonlinear temperaturereference representation includes a first normal nonlinear startuptemperature reference representation and a second higher emergencynonlinear temperature reference representation.
 68. A combustion turbineelectric power plant comprising a combustion turbine having compressor,combustion and turbine elements, a generator coupled to said combustionturbine for drive power, a fuel system for supplying fuel to saidcombustion turbine combustion element, means for operating said fuelsystem to energize said turbine, means for generating a turbine exhausttemperature limit representation as a function of an actual exhausttemperature representation and a representation of a nonlineartemperature reference characterization, applicable during loadoperation, and means for controlling said fuel system operating means asa function of said nonlinear temperature limit.
 69. An electric powerplant as set forth in claim 68 wherein said controlling means includes ablade path temperature limit control arrangement and an exhausttemperature limit control arrangement and said nonlinear temperaturereference is employed in both control arrangements.
 70. An electricpower plant as set forth in claim 68 wherein said nonlinear temperaturereference representation includes a first nonlinear temperaturereference representation and a second higher nonlinear temperaturereference representation and a third higher nonlinear temperaturerepresentation.
 71. A combustion turbine electric power plant comprisinga combustion turbine having compressor and combustion and turbineelements, a generator coupled to said combustion turbine for drivepower, a fuel system for supplying fuel to the combustion turbinecombustion element, means for operating said fuel system to energizesaid turbine, means for generating a turbine exhaust temperature limitrepresentation as a function of an actual exhaust temperaturerepresentation and a representation of a nonlinear temperature referencecharacterization applicable during startup operation, means forcontrolling said fuel system operating means as a function of anonlinear temperature limit, and means for detecting generator load, andmeans for controlling said fuel system operating means in response todetected load to regulate the generator load substantially to apredetermined value.
 72. Industrial combustion turbine apparatuscomprising a combustion turbine having compressor and combustion andturbine elements, a fuel system for supplying fuel to the combustionturbine combustion element, means for operating said fuel system toenergize said turbine, digital computer means and a signal input/outputmeans therefor, means for operating said computer means to determine afuel demand representation for desired turbine operation, means forcontrolling said fuel system operating means in accordance with the fueldemand representation, said fuel demand representation including a speeddemand representation which is converted to an analog output speedreference signal from said computer means, and said fuel systemcontrolling means includes means for detecting actual turbine speed andmeans for generating a fuel demand signal in response to the differencebetween the actual speed and the speed reference.
 73. Combustion turbineplant apparatus as set forth in claim 72 wherein the fuel demandrepresentation further includes at least one fuel demand limitrepresentation, and means are provided for operating said fuel demandsignal generating means in accordance with the lower fuel demand signalor representation.
 74. Combustion turbine plant apparatus as set forthin claim 73 wherein the fuel demand representation includes a pluralityof fuel demand limit representations.
 75. Combustion turbine plantapparatus as set forth in claim 74 wherein said computer operating meansprovides a low selection from the fuel demand limit representation forconversion to a single output fuel demand limit signal.
 76. Combustionturbine plant apparatus as set forth in claim 72 wherein means areprovided for generating an auxiliary backup speed signal, and means areprovided for limiting the fuel demand signal as a function of the backupspeed signal.
 77. Industrial combustion turbine apparatus comprising acombustion turbine having compressor and combustion and turbineelements, a fuel system for supplying fuel to the combustion turbinecombustion element, digital computer control means for generating a fueldemand signal as a function of speed demand during speed control and asa function of speed demand and load setpoint or limit demand during loadcontrol, means for generating said speed and load demands, means foroperating said fuel system to energize said turbine in response to saidfuel demand, and means for operating said computer means to limit therate at which said fuel demand representation changes during changes inthe load on the turbine.
 78. Industrial combustion turbine apparatuscomprising a combustion turbine having compressor and combustion andturbine elements, a fuel system for supplying fuel to the combustionturbine combustion element, digital computer control means forgenerating a fuel demand signal as a function of speed demand duringspeed control and as a function of speed demand and load setpoint orlimit demand during load control, means for generating said speed andload demands, means for operating said fuel system to energize saidturbine, means for operating said computer means to generate a turbineexhaust temperature reference representation of a nonlinear temperaturereference characterization to limit said speed demand during startupoperation, and means for controlling said fuel system operating means asa function of the nonlinear temperature reference.
 79. Industrialcombustion turbine apparatus comprising a combustion turbine havingcompressor and combustion and turbine elements, a fuel system forsupplying fuel to the combustion turbine combustion element, digitalcomputer control means for generating a fuel demand signal as a functionof speed demand during speed control and as a function of speed demandand load setpoint or limit demand during load control, means forgenerating said speed and load demands, means for operating said fuelsystem to energize said turbine, means for operating said computer meansto generate a turbine exhaust temperature reference representation of anonlinear temperature reference characterization to limit said loaddemand during turbine loading operation, and means for controlling saidfuel system operating means as a function of the nonlinear temperaturereference.
 80. Industrial combustion turbine apparatus comprising acombustion turbine having compressor and combustion and turbineelements, a fuel system for supplying fuel to the combustion turbinecombustion element, digital computer control means for generating a fueldemand signal as a function of speed demand during speed control and asa function of speed demand and load setpoint or limit demand during loadcontrol, means for generating said speed and load demands, means foroperating said fuel system to energize said turbine, means for operatingsaid computer means to generate a surge limit representation of anonlinear surge limit characterization to limit said speed demand duringturbine startup, and means for controlling said fuel system operatingmeans as a function of the nonlinear surge limit representation.
 81. Acomputer control system for operating industrial combustion turbineapparatus including a combustion turbine having compressor andcombustion and turbine elements and a fuel system for supplying fuel tothe combustion element, said control system comprising digital computermeans, signal input/output means for said computer means, means forcontrolling the operation of the fuel system, means for generating aturbine speed and other predetermined feedback signals, means foroperating said computer means to generate a feedforward speed referencerepresentation, said computer operating means further generating aturbine load level determining representation in response to at leastone of said other predetermined turbine signals, said computer operatingmeans combining said representations to generate a fuel demand, andmeans external to said computer means for controlling said fuel systemoperating means in response to the fuel demand and said speed signalmeans for turbine and generator speed control.
 82. A control system foroperating a combustion turbine-electric power plant including anelectric generator and a generator breaker and a combustion turbinehaving compressor and combustion and turbine elements and a fuel systemfor supplying fuel to the combustion element, said control systemcomprising digital computer means, signal input/output means for saidcomputer, means for controlling the operation of the generator breaker,means for controlling the operation of the fuel system, means foroperating said computer means to generate control outputs for both ofsaid controlling means, said computer operating means generating a fueldemand for turbine speed and load control in response to a turbine speeddemand and a turbine load setpoint or limit demand, means for generatingat least one of said speed and load demand signals in response to anonlinear turbine operating limit characterization, and means forcontrolling said fuel system operating means in response to a computermeans output signal corresponding to said fuel demand.
 83. A computercontrol system for operating industrial combustion turbine apparatus,including a combustion turbine having compressor and combustion andturbine elements and a fuel system for supplying fuel to the combustionelement, said control system comprising digital computer means, signalinput/output means for said computer means, means for detecting actualturbine speed, means for operating said computer means to generate anoutput speed reference demand during speed and load modes of operation,means for operating said computer means to generate a load setpoint orlimit demand signal during the load mode of operation, said computeroperating means combining said speed and load demands to generate aspeed fuel demand during startup and a load fuel demand during loadoperation, an analog speed control generating an output in response tothe actual speed and the reference fuel demand signals during thestartup and load mode, and means for controlling the operation of thefuel system as a function of the speed control output.
 84. A computercontrol system as set forth in claim 83 wherein said computer operatingmeans further generates at least one fuel demand limit representation,and means for limiting the operation of said fuel system controllingmeans in accordance with the fuel demand limit.
 85. A computer controlsystem as set forth in claim 84 wherein a plurality of fuel demand limitrepresentations are generated by said computer operating means and thelowest fuel demand limit is as an output for the operation of said fueloperation limiting means.
 86. A computer control system as set forth inclaim 84 wherein a non-linear startup surge limit representation isgenerated.
 87. A computer control system as set forth in claim 84wherein a non-linear startup and load exhaust temperature reference isgenerated by said computer operating means, means are provided fordetermining a temperature representative of actual exhaust temperature,and an exhaust temperature limit representation is generated as afunction of the actual and reference temperature representations.
 88. Acomputer control system as set forth in claim 87 wherein a non-linearstartup surge limit representation is generated and the lowest fueldemand limit is selected.
 89. A computer control system for operating anindustrial combustion turbine apparatus including a combustion turbinehaving compressor and combustion and turbine elements and a fuel systemfor supplying fuel to the combustion element, said control systemcomprising digital computer means, signal input/output means for saidcomputer means, means for controlling the operation of the fuel system,means for operating said computer means to generate a turbine exhausttemperature limit representation as a function of a determined exhausttemperature representation and a representation of a non-lineartemperature reference characterization applicable during startup andturbine loading operation, and means for controlling said fuel systemoperating means as a function of the non-linear temperature limit. 90.The method according to claim 4 wherein said second step of operatingthe computer includes the step of generating a surge limitrepresentation of a nonlinear surge limit characterization which iseffective during turbine startup.
 91. The method according to claim 90wherein said second step of operating the computer includes the step ofgenerating a generator load demand representation.
 92. The methodaccording to claim 90 wherein said second step of operating the computerincludes the step of generating a generator load demand representation.